feat: enable metrics in granian

This allows better understanding why the server is not responding.

Author: nijel

etc/supervisor/conf.d/web.conf

@@ -9,6 +9,7 @@ command = /app/venv/bin/granian
     --blocking-threads %(ENV_WEB_BLOCKING_THREADS)s
     --host 127.0.0.1
     --port 8081
+    --metrics
     %(ENV_GRANIAN_ARGS)s
     weblate.wsgi:application
 stdout_logfile=/dev/fd/1