wallpapers/potd: do not match colon in regex
Sometimes the author label does not contain a colon, for example, on 20220813, the author field does not contain a colon.
BUG: 457823 FIXED-IN: 5.25.5
Sometimes the author label does not contain a colon, for example, on 20220813, the author field does not contain a colon.
BUG: 457823 FIXED-IN: 5.25.5