Return immediately on request to /update.

The processing takes longer than the timeout, do it in the background.

brian_dashboard_manager/routes/update.py

+from concurrent.futures import ThreadPoolExecutor
 from flask import Blueprint, current_app
 from brian_dashboard_manager.routes import common
 from brian_dashboard_manager.grafana.provision import provision
@@ -13,5 +14,6 @@ def after_request(resp):
 
 @routes.route('/', methods=['GET'])
 def update():
-    success = provision(current_app.config[CONFIG_KEY])
-    return {'data': success}
+    executor = ThreadPoolExecutor(max_workers=1)
+    executor.submit(provision, current_app.config[CONFIG_KEY])
+    return {'data': {'message': 'Provisioning dashboards!'}}