Bump nokogiri from 1.6.6.4 to 1.10.4

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.6.6.4 to 1.10.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/master/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.6.6.4...v1.10.4)

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

Gemfile.lock

@@ -93,11 +93,11 @@ GEM
       rb-inotify (>= 0.9)
     maruku (0.7.0)
     mercenary (0.3.5)
-    mini_portile (0.6.2)
+    mini_portile2 (2.4.0)
     minitest (5.8.3)
     net-dns (0.8.0)
-    nokogiri (1.6.6.4)
-      mini_portile (~> 0.6.0)
+    nokogiri (1.10.4)
+      mini_portile2 (~> 2.4.0)
     parslet (1.5.0)
       blankslate (~> 2.0)
     posix-spawn (0.3.11)