Add more precise error message for Callable annotation (#12518)

Adds a more precise error message for a Callable annotation, if the
option --disallow-any-generics (part of --strict mode) has been used.
The suggestion in the old message was incorrect in this scenario.

Fixes #11757

mypy/typeanal.py

@@ -950,7 +950,10 @@ def analyze_callable_type(self, t: UnboundType) -> Type:
                     return AnyType(TypeOfAny.from_error)
                 ret = maybe_ret
         else:
-            self.fail('Please use "Callable[[<parameters>], <return type>]" or "Callable"', t)
+            if self.options.disallow_any_generics:
+                self.fail('Please use "Callable[[<parameters>], <return type>]"', t)
+            else:
+                self.fail('Please use "Callable[[<parameters>], <return type>]" or "Callable"', t)
             return AnyType(TypeOfAny.from_error)
         assert isinstance(ret, CallableType)
         return ret.accept(self)