Bump Rack from 2.0.8 to 2.1.2 (#12991)

* Update Gemfile

* Update Gemfile.lock

Gemfile

@@ -9,7 +9,7 @@ gem 'puma', '~> 4.3'
 gem 'rails', '~> 5.2.4'
 gem 'sprockets', '~> 3.7.2'
 gem 'thor', '~> 0.20'
-gem 'rack', '2.0.8'
+gem 'rack', '~> 2.1.2'
 
 gem 'thwait', '~> 0.1.0'
 gem 'e2mmap', '~> 0.1.0'

Gemfile.lock

@@ -44,7 +44,7 @@ GEM
     actionpack (5.2.4.1)
       actionview (= 5.2.4.1)
       activesupport (= 5.2.4.1)
-      rack (~> 2.0, >= 2.0.8)
+      rack (~> 2.0, >= 2.1.2)
       rack-test (>= 0.6.3)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.2)
@@ -148,7 +148,7 @@ GEM
       addressable
       mini_mime (>= 0.1.3)
       nokogiri (~> 1.8)
-      rack (>= 1.6.0)
+      rack (>= 2.1.2)
       rack-test (>= 0.6.3)
       regexp_parser (~> 1.5)
       xpath (~> 3.2)
@@ -441,7 +441,7 @@ GEM
     pundit (2.1.0)
       activesupport (>= 3.0.0)
     raabro (1.1.6)
-    rack (2.0.8)
+    rack (2.1.2)
     rack-attack (6.2.2)
       rack (>= 1.0, < 3)
     rack-cors (1.1.1)
@@ -749,7 +749,7 @@ DEPENDENCIES
   pry-rails (~> 0.3)
   puma (~> 4.3)
   pundit (~> 2.1)
-  rack (= 2.0.8)
+  rack (~> 2.1.2)
   rack-attack (~> 6.2)
   rack-cors (~> 1.1)
   rails (~> 5.2.4)