chore: ensure git blame remains informative

Author: maelle

.git-blame-ignore-rev

@@ -0,0 +1,8 @@
+# This file lists revisions of large-scale formatting/style changes so that
+# they can be excluded from git blame results.
+#
+# To set this file as the default ignore file for git blame, run:
+#   $ git config blame.ignoreRevsFile .git-blame-ignore-revs
+
+# https://github.com/r-lib/gert/pull/255
+4a7d8220d731efc1952f338e19258d3da3c88b0c