Bump nokogiri from 1.14.3 to 1.15.6

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.14.3 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@v1.14.3...v1.15.6)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -126,7 +126,7 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2020.1104)
     mini_mime (1.0.2)
-    mini_portile2 (2.8.1)
+    mini_portile2 (2.8.5)
     minitest (5.19.0)
     mongo (2.13.1)
       bson (>= 4.8.2, < 5.0.0)
@@ -157,15 +157,15 @@ GEM
       slack-ruby-bot (>= 0.10.5)
     newrelic_rpm (6.14.0)
     nio4r (2.5.4)
-    nokogiri (1.14.3)
-      mini_portile2 (~> 2.8.0)
+    nokogiri (1.15.6)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     oj (3.10.16)
     parallel (1.20.1)
     parser (2.7.2.0)
       ast (~> 2.4.1)
     public_suffix (4.0.6)
-    racc (1.6.2)
+    racc (1.7.3)
     rack (2.2.8.1)
     rack-accept (0.4.5)
       rack (>= 0.4)