sentry: add dependency on sentry_tunnel_ente branch

.gitmodules

@@ -9,7 +9,7 @@
 [submodule "thirdparty/sentry-dart"]
 	path = thirdparty/sentry-dart
 	url = https://github.com/ente-io/sentry-dart.git
-	 branch = sentry_tunnel
+	branch = sentry_flutter_ente
 
 [submodule "thirdparty/extended_image"]
     path = thirdparty/extended_image