Update to newer eventmachine

Gemfile

@@ -27,7 +27,7 @@ gem 'turbolinks'
 gem 'uglifier'
 gem 'tubesock', git: 'https://github.com/gosukiwi/tubesock', branch: 'patch-1' # Switch to a fork which is compatible with Rails 5
 gem 'faye-websocket'
-gem 'eventmachine', '1.0.9.1' # explicitly added, this is used by faye-websocket, newer versions might crash or
+gem 'eventmachine'
 gem 'nokogiri'
 gem 'webpacker'
 gem 'rest-client'
@@ -36,7 +36,7 @@ gem 'faraday'
 gem 'proforma', git: 'https://github.com/openHPI/proforma.git', tag: 'v0.5'
 gem 'whenever', require: false
 gem 'rails-timeago'
-gem 'rails_admin', '~> 2.0'
+gem 'rails_admin'
 
 # Error Tracing
 gem 'concurrent-ruby'

Gemfile.lock

@@ -123,7 +123,7 @@ GEM
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
     erubi (1.10.0)
-    eventmachine (1.0.9.1)
+    eventmachine (1.2.7)
     excon (0.78.1)
     execjs (2.7.0)
     factory_bot (6.1.0)
@@ -469,7 +469,7 @@ DEPENDENCIES
   concurrent-ruby
   database_cleaner
   docker-api
-  eventmachine (= 1.0.9.1)
+  eventmachine
   factory_bot_rails
   faraday
   faye-websocket
@@ -497,7 +497,7 @@ DEPENDENCIES
   rails-controller-testing
   rails-i18n
   rails-timeago
-  rails_admin (~> 2.0)
+  rails_admin
   ransack
   rest-client
   rspec-autotest