Add another fallback date for tracks

In some cases a track may not have an album release or track release date, in this case fallback to when the track was first added to Bandcamp.

bandcamp_dl/bandcamp.py

@@ -51,6 +51,8 @@ class Bandcamp:
         album_release = page_json['album_release_date']
         if album_release is None:
             album_release = page_json['current']['release_date']
+            if album_release is None:
+                album_release = page_json['embed_info']['item_public']
 
         try:
             album_title = page_json['current']['title']

requirements.txt

@@ -1,10 +1,10 @@
 --index-url https://pypi.python.org/simple/
 
-beautifulsoup4==4.10.0
+beautifulsoup4==4.11.1
 demjson3==3.0.5
 docopt==0.6.2
 mutagen==1.45.1
-requests==2.26.0
+requests==2.27.1
 unicode-slugify==0.1.5
 mock==4.0.3
 chardet==4.0.0