[Security] Bump nokogiri from 1.8.2 to 1.8.5 (#356)

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.8.2 to 1.8.5. **This update includes security fixes.**
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/master/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.8.2...v1.8.5)

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

Author: greysteil

Gemfile.lock

@@ -5,7 +5,7 @@ GEM
     diff-lcs (1.3)
     method_source (0.9.0)
     mini_portile2 (2.3.0)
-    nokogiri (1.8.2)
+    nokogiri (1.8.5)
       mini_portile2 (~> 2.3.0)
     pry (0.11.3)
       coderay (~> 1.1.0)