Respect the magic trailing comma in starred type parameter lists

A magic trailing comma exploded a PEP 695 type parameter list of plain
type vars, but was silently ignored once the list contained a
*TypeVarTuple or **ParamSpec, collapsing the params back onto one line.

is_split_before_delimiter/is_split_after_delimiter skip a star that
is_vararg() recognises, so it is not mistaken for a MATH_OPERATORS
delimiter. is_vararg() checks the star's parent against
VARARGS_PARENTS, which listed the argument and lambda nodes but not the
PEP 695 typevartuple and paramspec ones. The stars in a type parameter
list were therefore scored as multiplication and power operators, and
that delimiter beat the comma when the line was split.

Add both nodes to VARARGS_PARENTS. This affects def, async def, class
and type aliases alike.

Closes #5243

Author: dipakchaudhari12717

src/black/nodes.py

@@ -73,6 +73,8 @@
     syms.trailer,  # single argument to call
     syms.typedargslist,
     syms.varargslist,  # lambdas
+    syms.typevartuple,  # star in a PEP 695 type parameter list
+    syms.paramspec,  # double star in a PEP 695 type parameter list
 }
 UNPACKING_PARENTS: Final = {
     syms.atom,  # single element of a list or set literal

tests/data/cases/type_params.py

@@ -13,6 +13,12 @@ def it_gets_worse[WhatIsTheLongestTypeVarNameYouCanThinkOfEnoughToMakeBlackSplit
 
 def magic[Trailing, Comma,](): pass
 
+def magic_starred[T, *Ts, **P,](): pass
+
+class MagicStarred[T, *Ts, **P,]: pass
+
+type MagicStarredAlias[T, *Ts, **P,] = int
+
 def weird_syntax[T: lambda: 42, U: a or b](): pass
 
 def name_3[name_0: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa if aaaaaaaaaaa else name_3](): pass
@@ -62,6 +68,29 @@ def magic[
     pass
 
 
+def magic_starred[
+    T,
+    *Ts,
+    **P,
+]():
+    pass
+
+
+class MagicStarred[
+    T,
+    *Ts,
+    **P,
+]:
+    pass
+
+
+type MagicStarredAlias[
+    T,
+    *Ts,
+    **P,
+] = int
+
+
 def weird_syntax[T: lambda: 42, U: a or b]():
     pass