Revert release toolkit back to stable version (1.4.0)

I've done the `msgid` bugfix real-world testing I wanted to do. Now
switching back to the expected version.

Gemfile.lock

@@ -1,22 +1,3 @@
-GIT
-  remote: [email protected]:wordpress-mobile/release-toolkit
-  revision: 603e6f6a7ea9de03ffd7b8c1934efdc04eb98e2f
-  branch: develop
-  specs:
-    fastlane-plugin-wpmreleasetoolkit (1.4.0)
-      activesupport (~> 5)
-      bigdecimal (~> 1.4)
-      chroma (= 0.2.0)
-      diffy (~> 3.3)
-      git (~> 1.3)
-      jsonlint (~> 0.3)
-      nokogiri (~> 1.11)
-      octokit (~> 4.18)
-      parallel (~> 1.14)
-      progress_bar (~> 1.3)
-      rake (>= 12.3, < 14.0)
-      rake-compiler (~> 1.0)
-
 GEM
   remote: https://rubygems.org/
   specs:
@@ -182,6 +163,19 @@ GEM
       trainer
       xcodeproj
       xctest_list (>= 1.2.1)
+    fastlane-plugin-wpmreleasetoolkit (1.4.0)
+      activesupport (~> 5)
+      bigdecimal (~> 1.4)
+      chroma (= 0.2.0)
+      diffy (~> 3.3)
+      git (~> 1.3)
+      jsonlint (~> 0.3)
+      nokogiri (~> 1.11)
+      octokit (~> 4.18)
+      parallel (~> 1.14)
+      progress_bar (~> 1.3)
+      rake (~> 12.3)
+      rake-compiler (~> 1.0)
     ffi (1.15.0)
     fourflusher (2.3.1)
     fuzzy_match (2.0.4)
@@ -268,7 +262,7 @@ GEM
       options (~> 2.3.0)
     public_suffix (4.0.6)
     racc (1.5.2)
-    rake (13.0.6)
+    rake (12.3.3)
     rake-compiler (1.1.1)
       rake
     rchardet (1.8.0)
@@ -343,7 +337,7 @@ DEPENDENCIES
   fastlane-plugin-appcenter (~> 1.8)
   fastlane-plugin-sentry
   fastlane-plugin-test_center
-  fastlane-plugin-wpmreleasetoolkit!
+  fastlane-plugin-wpmreleasetoolkit (~> 1.4)
   octokit (~> 4.0)
   rake
   rmagick (~> 3.2.0)

fastlane/Pluginfile

@@ -6,7 +6,7 @@ group :screenshots, optional: true do
   gem 'rmagick', '~> 3.2.0'
 end
 
-gem 'fastlane-plugin-wpmreleasetoolkit', git: '[email protected]:wordpress-mobile/release-toolkit', branch: 'develop'
+gem 'fastlane-plugin-wpmreleasetoolkit', '~> 1.4'
 
 gem 'fastlane-plugin-sentry'
 gem 'fastlane-plugin-appcenter', '~> 1.8'