spotify: spotify_updated is always a "null" date
I just checked the `spotify_updated` values and all the values are `1969-12-31 19:00:00`, which prevents the use of any date-related queries. 
 
I have seen this elsewhere, but cannot figure out how to fix the issue. Here's how the date is currently being saved

https://github.com/beetbox/beets/blob/44a7cc74bfe673bcf960c5dc18716b38e33d5ad0/beetsplug/spotify.py#L651

Any idea how to fix it?

diff --git a/beetsplug/spotify.py b/beetsplug/spotify.py
index f1aecb583..66b2b1084 100644
--- a/beetsplug/spotify.py
+++ b/beetsplug/spotify.py
@@ -19,7 +19,6 @@ Spotify playlist construction.
 
 import base64
 import collections
-import datetime
 import json
 import re
 import time
@@ -648,7 +647,7 @@ class SpotifyPlugin(MetadataSourcePlugin, BeetsPlugin):
                 if feature in self.spotify_audio_features.keys():
                     item[self.spotify_audio_features[feature]] = \\
                         audio_features[feature]
-            item['spotify_updated'] = datetime.datetime.now()
+            item['spotify_updated'] = time.time()
             item.store()
             if write:
                 item.try_write()
['beetsplug/spotify.py']