[Security] Bump nokogiri from 1.10.7 to 1.10.8

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.10.7 to 1.10.8. **This update includes a security fix.**
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/master/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.10.7...v1.10.8)

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

Author: dependabot-preview[bot]

Gemfile.lock

@@ -82,7 +82,7 @@ GEM
     minitest (5.13.0)
     mustermann (1.0.3)
     nio4r (2.5.2)
-    nokogiri (1.10.7)
+    nokogiri (1.10.8)
       mini_portile2 (~> 2.4.0)
     rack (2.0.8)
     rack-protection (2.0.7)