Bump request_store gem

This allows us to use `RequestStore.store=` in specs. Which we can use
to isolate values for sidekiq jobs.

Gemfile

@@ -287,7 +287,7 @@ gem 'addressable', '~> 2.7'
 gem 'font-awesome-rails', '~> 4.7'
 gem 'gemojione', '~> 3.3'
 gem 'gon', '~> 6.2'
-gem 'request_store', '~> 1.3'
+gem 'request_store', '~> 1.5'
 gem 'base32', '~> 0.3.0'
 
 gem "gitlab-license", "~> 1.0"

Gemfile.lock

@@ -883,7 +883,8 @@ GEM
       declarative (< 0.1.0)
       declarative-option (< 0.2.0)
       uber (< 0.2.0)
-    request_store (1.3.1)
+    request_store (1.5.0)
+      rack (>= 1.4)
     responders (3.0.0)
       actionpack (>= 5.0)
       railties (>= 5.0)
@@ -1350,7 +1351,7 @@ DEPENDENCIES
   redis (~> 4.0)
   redis-namespace (~> 1.6.0)
   redis-rails (~> 5.0.2)
-  request_store (~> 1.3)
+  request_store (~> 1.5)
   responders (~> 3.0)
   retriable (~> 3.1.2)
   rouge (~> 3.18.0)