Embed this gem until gitlab moved to 7.x version

--- a/Gemfile
+++ b/Gemfile
@@ -140,7 +140,7 @@
 gem 'seed-fu', '~> 2.3', '>= 2.3.7'
 
 # Search
-gem 'elasticsearch-model', '~> 6.1'
+gem 'elasticsearch-model', '~> 6.1', path: 'vendor/gems/elasticsearch-model'
 gem 'elasticsearch-rails', '~> 6.1', require: 'elasticsearch/rails/instrumentation'
 gem 'elasticsearch-api',   '~> 6.8', '>= 6.8.2'
 gem 'aws-sdk-core', '~> 3'