po4a/update-po: Delete the *.po.authors files

These are temporary files that are needed only when running po4a.
The top-level Makefile.am puts the whole po4a directory into
distribution tarball (it's simpler) so deleting these temporary
files is needed to prevent them from getting into tarballs.

po4a/update-po

@@ -61,6 +61,10 @@ po4a --force --verbose \
 	--copyright-holder="The XZ Utils authors and contributors" \
 	po4a.conf
 
+# Remove the *.po.authors files that were generated above.
+# This way they won't get included in distribution tarballs.
+rm -f *.po.authors
+
 # Add the customized POT header which contains the SPDX license
 # identifier and spells out the license name instead of saying
 # "the same license as the XZ Utils package".