fix(sites): Remediate false positive for Spotify

- Changed errorType from 'status_code' to 'message'
- Added errorMsg check for 'Page not found'
- Updated username_claimed to 'spotify' (verified working)

Spotify returns HTTP 200 for both valid and invalid users, then
shows 'Page not found' in the HTML for non-existent profiles.
The previous status_code check caused false positives.

Tested with:
- Non-existent user: Correctly returns NOT FOUND
- Real user 'spotify': Correctly returns FOUND
- Verified against username_claimed

Fixes: #2547

sherlock_project/resources/data.json

@@ -2276,7 +2276,7 @@
     "errorType": "status_code",
     "url": "https://open.spotify.com/user/{}",
     "urlMain": "https://open.spotify.com/",
-    "username_claimed": "blue"
+    "username_claimed": "spotify"
   },
   "Star Citizen": {
     "errorMsg": "404",