Skip Youtube-API-only fields when scraping

This happens because YouTube recently disabled older API keys for some
reason, and so the API key being used internally in Pafy no longer
works.

See #671 for more information.

spotdl/youtube_tools.py

@@ -109,8 +109,8 @@ def generate_metadata(content):
             "artists": [{"name": None}],
             "name": None,
         },
-        "year": content.published.split("-")[0],
-        "release_date": content.published.split(" ")[0],
+        "year": None,
+        "release_date": None,
         "type": "track",
         "disc_number": 1,
         "track_number": 1,
@@ -122,6 +122,14 @@ def generate_metadata(content):
         "genre": None,
     }
 
+    # Workaround for
+    # https://github.com/ritiek/spotify-downloader/issues/671
+    try:
+        meta_tags["year"] = content.published.split("-")[0]
+        meta_tags["release_date"] = content.published.split(" ")[0]
+    except pafy.util.GdataError:
+        pass
+
     return meta_tags