Merge branch 'update-asset-sync' into 'master'

Update asset_sync ~> 2.2.0 to ~> 2.4

See merge request gitlab-org/gitlab-ce!18762

Gemfile

@@ -434,4 +434,4 @@ gem 'lograge', '~> 0.5'
 gem 'grape_logging', '~> 1.7'
 
 # Asset synchronization
-gem 'asset_sync', '~> 2.2.0'
+gem 'asset_sync', '~> 2.4'

Gemfile.lock

@@ -59,7 +59,7 @@ GEM
     asciidoctor (1.5.6.2)
     asciidoctor-plantuml (0.0.8)
       asciidoctor (~> 1.5)
-    asset_sync (2.2.0)
+    asset_sync (2.4.0)
       activemodel (>= 4.1.0)
       fog-core
       mime-types (>= 2.99)
@@ -197,7 +197,7 @@ GEM
     et-orbi (1.0.3)
       tzinfo
     eventmachine (1.0.8)
-    excon (0.60.0)
+    excon (0.62.0)
     execjs (2.6.0)
     expression_parser (0.9.0)
     factory_bot (4.8.2)
@@ -998,7 +998,7 @@ DEPENDENCIES
   asana (~> 0.6.0)
   asciidoctor (~> 1.5.6)
   asciidoctor-plantuml (= 0.0.8)
-  asset_sync (~> 2.2.0)
+  asset_sync (~> 2.4)
   attr_encrypted (~> 3.1.0)
   awesome_print (~> 1.2.0)
   babosa (~> 1.0.2)