remove deprecated numpy.typing.mypy_plugin in mypy.ini (pytorch#156601)

Fixes pytorch#156489
removed deprecated numpy plugin in mypy.ini
 @ezyang
Pull Request resolved: pytorch#156601
Approved by: https://github.com/ezyang

Author: morrison-turnansky

mypy.ini

@@ -2,7 +2,7 @@
 # test_run_mypy in test/test_type_hints.py uses this string)
 
 [mypy]
-plugins = mypy_plugins/check_mypy_version.py, mypy_plugins/sympy_mypy_plugin.py, numpy.typing.mypy_plugin
+plugins = mypy_plugins/check_mypy_version.py, mypy_plugins/sympy_mypy_plugin.py
 
 cache_dir = .mypy_cache/normal
 allow_redefinition = True