Get the gid from the branch dict when not encrypted

See ValvePython#476

Author: fabieu

steam/client/cdn.py

@@ -829,9 +829,9 @@ def async_fetch_manifest(
                     manifest_gid = decrypt_manifest_gid_2(unhexlify(egid),
                                                           self.beta_passwords[(app_id, branch)])
                 else:
-                    manifest_gid = depot_info.get('manifests', {}).get('public')
+                    manifest_gid = depot_info.get('manifests', {}).get('public').get('gid')
             else:
-                manifest_gid = depot_info.get('manifests', {}).get(branch)
+                manifest_gid = depot_info.get('manifests', {}).get(branch).get('gid')
 
             if manifest_gid is not None:
                 tasks.append(