bump version to 0.7.8+408

pubspec.yaml

@@ -12,7 +12,7 @@ description: ente photos application
 # Read more about iOS versioning at
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 
-version: 0.7.7+407
+version: 0.7.8+408
 
 environment:
   sdk: '>=2.17.0 <3.0.0'