black: also ignore grey.py

Differential Revision: https://phab.mercurial-scm.org/D7090

black.toml

@@ -11,6 +11,7 b' build/'
 | mercurial/thirdparty/
 | hgext/fsmonitor/pywatchman/
 | contrib/python-zstandard/
+| contrib/grey.py
 '''
 skip-string-normalization = true
 quiet = true

contrib/examples/fix.hgrc

@@ -12,4 +12,4 b' rustfmt:pattern = set:**.rs'
 # to have the dependencies for grey.
 #
 # black:command = python3.7 contrib/grey.py --config=black.toml -
-# black:pattern = set:**.py - hgext/fsmonitor/pywatchman/** - mercurial/thirdparty/** - "contrib/python-zstandard/**"
+# black:pattern = set:**.py - hgext/fsmonitor/pywatchman/** - mercurial/thirdparty/** - "contrib/python-zstandard/** - contrib/grey.py"