clarify "open issues" text for labels (#22431)

see also https://codeberg.org/Codeberg/Community/issues/877

options/locale/locale_en-US.ini

@@ -1379,7 +1379,7 @@ issues.label_title = Label name
 issues.label_description = Label description
 issues.label_color = Label color
 issues.label_count = %d labels
-issues.label_open_issues = %d open issues
+issues.label_open_issues = %d open issues/pull requests
 issues.label_edit = Edit
 issues.label_delete = Delete
 issues.label_modify = Edit Label