misc: fix spurious errors with non-en-frontpage-news (#5265)

Before if none of the files submitted to the check contained the tag, and there were hence no matches the script would fail incorrectly.

This is no longer the case

Co-authored-by: Darragh Elliott <me@delliott.net>
Reviewed-on: #5265
Co-authored-by: delliott <delliott@fsfe.org>
Co-committed-by: delliott <delliott@fsfe.org>

tools/ci-checks/check-non-en-frontpage.sh

@@ -7,7 +7,7 @@ set -euo pipefail
 
 # select all items which have the front-page tag
 exit=0
-matched_files="$(grep "<tag.*front-page" --files-with-matches "$@")"
+matched_files="$(grep "<tag.*front-page" --files-with-matches "$@" || true)"
 
 for file in $matched_files; do
 	base="${file%.*}"  # file.xx