Update version of stage_file_proxy

composer.json

@@ -82,7 +82,7 @@
     "drupal/smart_date": "^4.1",
     "drupal/smtp": "^1.2",
     "drupal/sqrl": "^2.0",
-    "drupal/stage_file_proxy": "^2.1",
+    "drupal/stage_file_proxy": "^3.1",
     "drupal/token": "^1.11",
     "drush/drush": "^12||^13",
     "lakedrops/ahoy": "^1.7||dev-develop",