NXD: get mimemagic from github

mimemagic was yanked from rubygems, so this cause gitlab to fail building. To
make it possible to keep installing this old version of gitlab we get mimemagic
from git.

Gemfile

@@ -268,7 +268,7 @@ gem 'ace-rails-ap', '~> 4.1.0'
 gem 'charlock_holmes', '~> 0.7.5'
 
 # Detect mime content type from content
-gem 'mimemagic', '~> 0.3.2'
+gem "mimemagic", git: "https://github.com/mimemagicrb/mimemagic"
 
 # Faster blank
 gem 'fast_blank'

Gemfile.lock

+GIT
+  remote: https://github.com/mimemagicrb/mimemagic
+  revision: d5ebc0cd846dcc68142622c76ad71d021768b7c2
+  specs:
+    mimemagic (0.3.3)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -1292,9 +1298,9 @@ DEPENDENCIES
   lru_redux
   mail (= 2.7.1)
   marginalia (~> 1.8.0)
+  mimemagic!
   memory_profiler (~> 0.9)
   method_source (~> 0.8)
-  mimemagic (~> 0.3.2)
   mini_magick
   minitest (~> 5.11.0)
   nakayoshi_fork (~> 0.0.4)