Fix a bug where SIG API spots could be re-tagged as another SIG e.g. WAB if that was named in the comment.

spotproviders/pota.py

@@ -31,6 +31,7 @@ class POTA(HTTPSpotProvider):
                         freq=float(source_spot["frequency"]) * 1000,
                         mode=source_spot["mode"].upper(),
                         comment=source_spot["comments"],
+                        sig="POTA",
                         sig_refs=[SIGRef(id=source_spot["reference"], sig="POTA", name=source_spot["name"])],
                         time=datetime.strptime(source_spot["spotTime"], "%Y-%m-%dT%H:%M:%S").replace(
                             tzinfo=pytz.UTC).timestamp(),