Use new mail_room fork

Update Gemfile with new mail_room fork
instead of the maintainer's original.
This allows us to release and use functionality earlier,
and to quickly pivot and customise based on immediate needs.

Gemfile

@@ -419,7 +419,8 @@ end
 
 gem 'octokit', '~> 4.15'
 
-gem 'mail_room', '~> 0.10.0'
+# https://gitlab.com/gitlab-org/gitlab/issues/207207
+gem 'gitlab-mail_room', '~> 0.0.2', require: 'mail_room'
 
 gem 'email_reply_trimmer', '~> 0.1'
 gem 'html2text'

Gemfile.lock

@@ -388,6 +388,7 @@ GEM
       opentracing (~> 0.4)
       redis (> 3.0.0, < 5.0.0)
     gitlab-license (1.0.0)
+    gitlab-mail_room (0.0.1)
     gitlab-markup (1.7.0)
     gitlab-net-dns (0.9.1)
     gitlab-puma (4.3.1.gitlab.2)
@@ -616,7 +617,6 @@ GEM
     lumberjack (1.0.13)
     mail (2.7.1)
       mini_mime (>= 0.1.1)
-    mail_room (0.10.0)
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     marginalia (1.8.0)
@@ -1235,6 +1235,7 @@ DEPENDENCIES
   gitlab-chronic (~> 0.10.5)
   gitlab-labkit (= 0.10.0)
   gitlab-license (~> 1.0)
+  gitlab-mail_room (~> 0.0.1)
   gitlab-markup (~> 1.7.0)
   gitlab-net-dns (~> 0.9.1)
   gitlab-puma (~> 4.3.1.gitlab.2)
@@ -1284,7 +1285,6 @@ DEPENDENCIES
   loofah (~> 2.2)
   lru_redux
   mail (= 2.7.1)
-  mail_room (~> 0.10.0)
   marginalia (~> 1.8.0)
   memory_profiler (~> 0.9)
   method_source (~> 0.8)