Bump nokogiri from 1.10.4 to 1.10.8

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.10.4 to 1.10.8.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/master/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.10.4...v1.10.8)

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

Gemfile.lock

@@ -154,7 +154,7 @@ GEM
     multi_json (1.13.1)
     multipart-post (2.0.0)
     netrc (0.11.0)
-    nokogiri (1.10.4)
+    nokogiri (1.10.8)
       mini_portile2 (~> 2.4.0)
     padrino-helpers (0.12.9)
       i18n (~> 0.6, >= 0.6.7)