build: bump public_suffix from 3.1.0 to 3.1.1 in /docs

Bumps [public_suffix](https://github.com/weppos/publicsuffix-ruby) from 3.1.0 to 3.1.1.
- [Release notes](https://github.com/weppos/publicsuffix-ruby/releases)
- [Changelog](https://github.com/weppos/publicsuffix-ruby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/weppos/publicsuffix-ruby/compare/v3.1.0...v3.1.1

)

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

docs/Gemfile.lock

@@ -221,7 +221,7 @@ GEM
     parallel (1.17.0)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (3.1.0)
+    public_suffix (3.1.1)
     rainbow (3.0.0)
     rake (12.3.2)
     rb-fsevent (0.10.3)