add missing comma to `run_test.py` (#57010)
Summary:
Factored out from https://github.com/pytorch/pytorch/pull/57008#discussion_r621137121:
> Without this comma, the strings are concatenated to `test_binary_ufuncstest_numpy_interop`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/57010
Reviewed By: malfet
Differential Revision: D28028061
Pulled By: walterddr
fbshipit-source-id: 97c64b79a6aaaf0242def03c8808c1a032537258
