tools: exclude Weblate bot from "ninja git-contrib"

Bots are not people, no reason to say thanks to them and list them as
authors or contributors.

tools/git-contrib.sh

@@ -2,6 +2,6 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -eu
 
-git shortlog -s `git describe --abbrev=0 --match 'v[0-9][0-9][0-9]'`.. | \
+git shortlog --author=noreply@weblate.org --invert-grep -s `git describe --abbrev=0 --match 'v[0-9][0-9][0-9]'`.. | \
     awk '{ $1=""; print $0 "," }' | \
     sort -u