Bump `parser` gem to 2.5.0.5

1. Synchronize used version of `parser` gem for both versions of rails: 4 and 5.
2. Fix broken CI pipelines for rails5 branches.

The 2.5.0.4 version is removed from rubygems, so it's skipped.
https://github.com/whitequark/parser/issues/478

Gemfile.lock

@@ -587,7 +587,7 @@ GEM
     orm_adapter (0.5.0)
     os (0.9.6)
     parallel (1.12.1)
-    parser (2.5.0.3)
+    parser (2.5.0.5)
       ast (~> 2.4.0)
     parslet (1.5.0)
       blankslate (~> 2.0)

Gemfile.rails5.lock

@@ -291,7 +291,7 @@ GEM
       po_to_json (>= 1.0.0)
       rails (>= 3.2.0)
     gherkin-ruby (0.3.2)
-    gitaly-proto (0.91.0)
+    gitaly-proto (0.94.0)
       google-protobuf (~> 3.1)
       grpc (~> 1.0)
     github-linguist (5.3.3)
@@ -587,7 +587,7 @@ GEM
     orm_adapter (0.5.0)
     os (0.9.6)
     parallel (1.12.1)
-    parser (2.5.0.4)
+    parser (2.5.0.5)
       ast (~> 2.4.0)
     parslet (1.5.0)
       blankslate (~> 2.0)
@@ -1062,7 +1062,7 @@ DEPENDENCIES
   gettext (~> 3.2.2)
   gettext_i18n_rails (~> 1.8.0)
   gettext_i18n_rails_js (~> 1.3)
-  gitaly-proto (~> 0.91.0)
+  gitaly-proto (~> 0.94.0)
   github-linguist (~> 5.3.3)
   gitlab-flowdock-git-hook (~> 1.0.1)
   gitlab-markup (~> 1.6.2)