Merge pull request #118 from gares/elpi-3.0

Adapt to rocq-prover/rocq#20887 (elpi 3.0)

Author: pi8027

Make

@@ -5,3 +5,5 @@ theories/ring.v
 -R theories mathcomp.algebra_tactics
 -arg -w -arg -notation-overridden
 -arg -w -arg +elpi.typecheck
+-arg -w -arg -elpi.typecheck-syntax # remove `Elpi Typecheck`, automatic with elpi 3
+-arg -w -arg -elpi.flex-clause      # use `X =!=> ...` instead if X is a rule for a function

_CoqProject

@@ -1,3 +1,5 @@
 -R theories mathcomp.algebra_tactics
 -arg -w -arg -notation-overridden
 -arg -w -arg +elpi.typecheck
+-arg -w -arg -elpi.typecheck-syntax # remove `Elpi Typecheck`, automatic with elpi 3
+-arg -w -arg -elpi.flex-clause      # use `X =!=> ...` instead if X is a rule for a function