Bump CarrierWave to 1.3.1

This avoids an extra HEAD request when making request for auth URL.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/56096

Gemfile.lock

@@ -108,7 +108,7 @@ GEM
     capybara-screenshot (1.0.22)
       capybara (>= 1.0, < 4)
       launchy
-    carrierwave (1.3.0)
+    carrierwave (1.3.1)
       activemodel (>= 4.0.0)
       activesupport (>= 4.0.0)
       mime-types (>= 1.16)