Update JSONSchemer to newest version

The issues with the unrecognized type have been resolved, allowing us to upgrade again.

Gemfile

@@ -19,7 +19,7 @@ gem 'http_accept_language'
 gem 'i18n-js'
 gem 'ims-lti', '< 2.0.0' # Version 2 implements LTI 2.0, which is deprecated. Hence, we stay with version 1.
 gem 'jbuilder'
-gem 'json_schemer', '< 2.0.0' # Version 2 currently has a bug that prevents validating timeout messages. See https://github.com/openHPI/codeocean/issues/1914
+gem 'json_schemer'
 gem 'js-routes'
 gem 'jwt'
 gem 'kramdown'

Gemfile.lock

@@ -182,7 +182,7 @@ GEM
     js-routes (2.2.7)
       railties (>= 4)
     json (2.6.3)
-    json_schemer (1.0.3)
+    json_schemer (2.0.0)
       hana (~> 1.3)
       regexp_parser (~> 2.0)
       simpleidn (~> 0.2)
@@ -555,7 +555,7 @@ DEPENDENCIES
   ims-lti (< 2.0.0)
   jbuilder
   js-routes
-  json_schemer (< 2.0.0)
+  json_schemer
   jwt
   kramdown
   letter_opener