Bump nokogiri from 1.15.5 to 1.15.6

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.15.5 to 1.15.6.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.15.5...v1.15.6)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile

@@ -22,7 +22,7 @@ gem 'jquery-rails', '= 4.0.5'
 gem 'jquery-ui-rails', '= 5.0.5'
 gem 'json', '>= 2.0'            # see https://github.com/flori/json/issues/399 - avoid deprecation warning with json 1.8.6
 gem 'newrelic_rpm'
-gem 'nokogiri', '~> 1.12'
+gem 'nokogiri', '~> 1.15'
 gem 'platform-api'                # for restart task
 gem 'responders', '~> 2.0'
 gem 'attr_encrypted'            # attr_encrypted must load AFTER protected_attributes (https://github.com/attr-encrypted/attr_encrypted/issues/107)

Gemfile.lock

@@ -178,7 +178,7 @@ GEM
     multipart-post (2.0.0)
     newrelic_rpm (5.0.0.342)
     nio4r (2.5.8)
-    nokogiri (1.15.5)
+    nokogiri (1.15.6)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     parallel (1.12.1)
@@ -383,7 +383,7 @@ DEPENDENCIES
   launchy
   listen (~> 2.2)
   newrelic_rpm
-  nokogiri (~> 1.12)
+  nokogiri (~> 1.15)
   pg (= 0.20)
   platform-api
   pry