Bump nokogiri in /notification-handler/spec/support/rails_app (#114)

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.10.3 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@v1.10.3...v1.10.4)

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

notification-handler/spec/support/rails_app/Gemfile.lock

@@ -104,7 +104,7 @@ GEM
     msgpack (1.2.10)
     multi_json (1.13.1)
     nio4r (2.3.1)
-    nokogiri (1.10.3)
+    nokogiri (1.10.4)
       mini_portile2 (~> 2.4.0)
     public_suffix (3.0.3)
     puma (3.12.1)