Restrict * methods for SimplePoly to Number's

[JamesWrigley]

I think it should still be ok for differentiating through expint() with ForwardDiff, since Dual <: Real.

Fixes these invalidations seen when loading CurveFit.jl on 1.13:

 inserting *(p::SpecialFunctions.SimplePoly, c) @ SpecialFunctions ~/.julia/packages/SpecialFunctions/pIm7V/src/expint.jl:8 invalidated:                                                                                                       
   mt_backedges:  1: signature Tuple{typeof(*), Any, Nothing} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Nothing, ::Nothing) (0 children)                                                                                 
                  2: signature Tuple{typeof(*), Any, Compiler.ConstResult} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::T, ::T) where T<:Compiler.ConstResult (0 children)                                                  
                  3: signature Tuple{typeof(*), Any, Compiler.CallMeta} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.CallMeta, ::Compiler.CallMeta) (0 children)                                                   
                  4: signature Tuple{typeof(*), Any, Compiler.MethodMatchInfo} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.MethodMatchInfo, ::Compiler.MethodMatchInfo) (0 children)                              
                  5: signature Tuple{typeof(*), Any, Compiler.AbstractIterationInfo} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.AbstractIterationInfo, ::Compiler.AbstractIterationInfo) (0 children)            
                  6: signature Tuple{typeof(*), Any, Compiler.ApplyCallInfo} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.ApplyCallInfo, ::Compiler.ApplyCallInfo) (0 children)                                    
                  7: signature Tuple{typeof(*), Any, Compiler.NewPhiCNode2} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.NewPhiCNode2, ::Compiler.NewPhiCNode2) (0 children)                                       
                  8: signature Tuple{typeof(*), Any, Compiler.ConstResult} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::T, ::T) where T<:Compiler.ConstResult (1 children)                                                  
                  9: signature Tuple{typeof(*), Any, Compiler.AbstractIterationInfo} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.AbstractIterationInfo, ::Compiler.AbstractIterationInfo) (1 children)            
                 10: signature Tuple{typeof(*), Any, Module} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Module, ::Module) (4 children)                                                                                    
                 11: signature Tuple{typeof(*), Any, Compiler.CallMeta} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.CallMeta, ::Compiler.CallMeta) (10 children)                                                  
                 12: signature Tuple{typeof(*), Any, Compiler.MethodMatchInfo} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.MethodMatchInfo, ::Compiler.MethodMatchInfo) (10 children)                             
                 13: signature Tuple{typeof(*), Any, Compiler.ApplyCallInfo} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.ApplyCallInfo, ::Compiler.ApplyCallInfo) (10 children)                                   
                 14: signature Tuple{typeof(*), Any, Compiler.NewPhiCNode2} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Compiler.NewPhiCNode2, ::Compiler.NewPhiCNode2) (10 children)                                      
                 15: signature Tuple{typeof(*), Any, Tuple{LineNumberNode, Expr}} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Tuple{LineNumberNode, Expr}, ::Tuple{LineNumberNode, Expr}) (11 children)                    
                 16: signature Tuple{typeof(*), Any, Nothing} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::Nothing, ::Nothing) (20 children)                                                                                
                 17: signature Tuple{typeof(*), Any, String} triggered MethodInstance for Base.lerpi(::Integer, ::Integer, ::String, ::String) (644 children)                                                                                  

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.49%. Comparing base (42ec04a) to head (4b03347).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #539   +/-   ##
=======================================
  Coverage   94.49%   94.49%           
=======================================
  Files          14       14           
  Lines        3016     3016           
=======================================
  Hits         2850     2850           
  Misses        166      166           

Flag	Coverage Δ
unittests	94.49% <100.00%> (ø)

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[JamesWrigley]

AFAICT the test failures are unrelated.

[devmotion]

Do we actually need both forms? AFAICT SimplePoly is completely internal, so likely one form should be sufficient?

[JamesWrigley]

I think that's a question for you and the other maintainers, I'm not at all familiar with the internals 😅 When it comes to invalidations I don't think it would matter.