Update gon gem to 6.4.0

It fixes the 2.7 warnings that are more visible as:
devise-4.7.3/lib/devise/test/controller_helpers.rb:35

The old version of gon didn't propagate kwargs properly to
Devise's process method.

CHANGELOG: https://github.com/gazay/gon/blob/master/CHANGELOG.md

Gemfile

@@ -294,7 +294,7 @@ gem 'terser', '1.0.2'
 
 gem 'addressable', '~> 2.7'
 gem 'gemojione', '~> 3.3'
-gem 'gon', '~> 6.2'
+gem 'gon', '~> 6.4.0'
 gem 'request_store', '~> 1.5'
 gem 'base32', '~> 0.3.0'
 

Gemfile.lock

@@ -499,8 +499,9 @@ GEM
       rubyntlm (~> 0.5)
     globalid (0.4.2)
       activesupport (>= 4.2.0)
-    gon (6.2.0)
-      actionpack (>= 3.0)
+    gon (6.4.0)
+      actionpack (>= 3.0.20)
+      i18n (>= 0.7)
       multi_json
       request_store (>= 1.0)
     google-api-client (0.50.0)
@@ -1444,7 +1445,7 @@ DEPENDENCIES
   gitlab-styles (~> 6.2.0)
   gitlab_chronic_duration (~> 0.10.6.2)
   gitlab_omniauth-ldap (~> 2.1.1)
-  gon (~> 6.2)
+  gon (~> 6.4.0)
   google-api-client (~> 0.33)
   google-protobuf (~> 3.14.0)
   gpgme (~> 2.0.19)

changelogs/unreleased/id-bump-gon-version.yml

+---
+title: Update gon gem to 6.4.0
+merge_request: 51210
+author:
+type: other

spec/deprecation_toolkit_env.rb

@@ -56,7 +56,6 @@ module DeprecationToolkitEnv
   def self.allowed_kwarg_warning_paths
     %w[
       activerecord-6.0.3.4/lib/active_record/migration.rb
-      devise-4.7.3/lib/devise/test/controller_helpers.rb
       activesupport-6.0.3.4/lib/active_support/cache.rb
       batch-loader-1.4.0/lib/batch_loader/graphql.rb
       carrierwave-1.3.1/lib/carrierwave/sanitized_file.rb