Update grafana/promtail Docker tag to v3

manifests/nextcloud_chart/manifest.yaml

@@ -56,9 +56,7 @@ data:
   general.config.php: |-
     <?php
     $CONFIG = array (
-        'overwriteprotocol' => 'https',
+        'overwriteprotocol' => 'https'
-        'loglevel' => 1,
-        'log_rotate_size' => 100 * 1024 * 1024
     );
   .htaccess: |-
     # line below if for Apache 2.4