`get_album` returns invalid artist data for track items in 1.7.4

[MarvinSchenkel]

As of 1.7.4, I am seeing invalid data returned for the track items list that is returned by the get_album function.

Here is the debug output of an album with id "MPREb_OUaeJveVKM0":
1.7.4

1.7.3

Additional context
Add any other context about the problem here, such as a code sample.

[czifumasa]

I think it's the result of my changes in #612.

Here's response from browse:

{"flexColumns": [
                                               {
                                                   "musicResponsiveListItemFlexColumnRenderer": {
                                                       "text": {
                                                           "runs": [
                                                               {
                                                                   "text": "Nothing Left at All",
                                                                   "navigationEndpoint": {
                                                                       "clickTrackingParams": "CKoBEMn0AhgCIhMI6tfftM2ehwMVEtBCBR3Vag8w",
                                                                       "watchEndpoint": {
                                                                           "videoId": "wJwY5KWJElk",
                                                                           "playlistId": "OLAK5uy_lnl2JfXqexo-ry4GFbw5EXZVuSM9MEEvU",
                                                                           "loggingContext": {
                                                                               "vssLoggingContext": {
                                                                                   "serializedContextData": "GilPTEFLNXV5X2xubDJKZlhxZXhvLXJ5NEdGYnc1RVhaVnVTTTlNRUV2VQ%3D%3D"
                                                                               }
                                                                           },
                                                                           "watchEndpointMusicSupportedConfigs": {
                                                                               "watchEndpointMusicConfig": {
                                                                                   "musicVideoType": "MUSIC_VIDEO_TYPE_ATV"
                                                                               }
                                                                           }
                                                                       }
                                                                   }
                                                               }
                                                           ]
                                                       },
                                                       "displayPriority": "MUSIC_RESPONSIVE_LIST_ITEM_COLUMN_DISPLAY_PRIORITY_HIGH"
                                                   }
                                               },
                                               {
                                                   "musicResponsiveListItemFlexColumnRenderer": {
                                                       "text": {},
                                                       "displayPriority": "MUSIC_RESPONSIVE_LIST_ITEM_COLUMN_DISPLAY_PRIORITY_HIGH"
                                                   }
                                               },
                                               {
                                                   "musicResponsiveListItemFlexColumnRenderer": {
                                                       "text": {
                                                           "runs": [
                                                               {
                                                                   "text": "44M plays"
                                                               }
                                                           ]
                                                       },
                                                       "displayPriority": "MUSIC_RESPONSIVE_LIST_ITEM_COLUMN_DISPLAY_PRIORITY_HIGH"
                                                   }
                                               }
                                           ]}

This is a flexColumn for an artist:

{
"musicResponsiveListItemFlexColumnRenderer": {
  "text": {},
 "displayPriority": "MUSIC_RESPONSIVE_LIST_ITEM_COLUMN_DISPLAY_PRIORITY_HIGH"
 }
}

it was skipped in parsing, because it was empty and then "Plays" column has been used as an artist. I will send PR with a fix.