Clean patches workflow: Fix RegExp for issue extraction (#275)
Clean patches workflow: Fix RegExp for issue extraction (#275)

The workflow failed to detect a second issue URL on the following line on
systems that have `\n` as line separator.

The fix is to use lookahead and lookbehind assertions instead of non-capturing
groups, so as not to "consume" bounding characters.
tidoust/reffy-reports,tidoust/reffy-reports