Remove fake shim for mimemagic

Since we upgrade to Rails 6.0.3.6 which no longer uses mimemagic, we can
now remove the fake shim for mimemagic.

Gemfile

@@ -278,9 +278,6 @@ gem 'charlock_holmes', '~> 0.7.7'
 # Detect mime content type from content
 gem 'ruby-magic', '~> 0.4'
 
-# Fake version of the gem to trick bundler
-gem 'mimemagic', '0.3.7', path: 'vendor/shims/mimemagic', require: false
-
 # Faster blank
 gem 'fast_blank'
 

Gemfile.lock

@@ -5,11 +5,6 @@ PATH
       connection_pool (~> 2.0)
       mail (~> 2.7)
 
-PATH
-  remote: vendor/shims/mimemagic
-  specs:
-    mimemagic (0.3.7)
-
 GEM
   remote: https://rubygems.org/
   specs:
@@ -1497,7 +1492,6 @@ DEPENDENCIES
   marginalia (~> 1.10.0)
   memory_profiler (~> 0.9)
   method_source (~> 1.0)
-  mimemagic (= 0.3.7)!
   mini_magick (~> 4.10.1)
   minitest (~> 5.11.0)
   multi_json (~> 1.14.1)

vendor/shims/mimemagic/Gemfile

-source "https://rubygems.org"
-
-# Specify your gem's dependencies in mimemagic.gemspec
-gemspec
-
-gem "rake", "~> 12.0"

vendor/shims/mimemagic/Gemfile.lock

-PATH
-  remote: .
-  specs:
-    mimemagic (0.3.7)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    rake (12.3.3)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  mimemagic!
-  rake (~> 12.0)
-
-BUNDLED WITH
-   2.1.4

vendor/shims/mimemagic/LICENSE.txt

-The MIT License (MIT)
-
-Copyright (c) 2021 GitLab B.V.
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in
-all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-THE SOFTWARE.

vendor/shims/mimemagic/README.md

-This is a fake gem to prevent mimemagic from being included into GitLab.

vendor/shims/mimemagic/Rakefile

-require "bundler/gem_tasks"
-task :default => :spec

vendor/shims/mimemagic/lib/mimemagic.rb

-require "mimemagic/version"
-
-module MimeMagic
-  class Error < StandardError; end
-  raise Error, 'This gem should never be required'
-end

vendor/shims/mimemagic/lib/mimemagic/version.rb

-module MimeMagic
-  VERSION = "0.3.7"
-end

vendor/shims/mimemagic/mimemagic.gemspec

-require_relative 'lib/mimemagic/version'
-
-Gem::Specification.new do |spec|
-  spec.name          = "mimemagic"
-  spec.version       = MimeMagic::VERSION
-  spec.authors       = ["Marc Shaw"]
-  spec.email         = ["mshaw@gitlab.com"]
-
-  spec.summary       = %q{MimeMagic shim}
-  spec.description   = %q{A shim for mimemagic}
-  spec.homepage      = "https://gitlab.com/gitlab-org/gitlab/-/tree/master/vendor/shims/mimemagic"
-  spec.license       = "MIT"
-  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
-
-  spec.files = %w[lib/mimemagic.rb lib/mimemagic/version.rb]
-
-  spec.require_paths = ["lib"]
-end