Bump chartkick from 5.0.3 to 5.0.4

Bumps [chartkick](https://github.com/ankane/chartkick) from 5.0.3 to 5.0.4.
- [Changelog](https://github.com/ankane/chartkick/blob/master/CHANGELOG.md)
- [Commits](ankane/chartkick@v5.0.3...v5.0.4)

---
updated-dependencies:
- dependency-name: chartkick
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -73,7 +73,7 @@ GEM
       msgpack (~> 1.2)
     builder (3.2.4)
     byebug (11.1.3)
-    chartkick (5.0.3)
+    chartkick (5.0.4)
     concurrent-ruby (1.2.2)
     connection_pool (2.4.1)
     crass (1.0.6)