Vladislav Zavialov authored Jul 29, 2023 and Marge Bot committed Dec 11, 2023

Before this change, GHC used to accept `forall` as a term-level
identifier:

	-- from constraints-0.13
	forall :: forall p. (forall a. Dict (p a)) -> Dict (Forall p)
	forall d = ...

Now it is a parse error.

The -Wforall-identifier warning has served its purpose and is now
a deprecated no-op.