Bump chartkick from 5.1.2 to 5.1.3

Bumps [chartkick](https://github.com/ankane/chartkick) from 5.1.2 to 5.1.3.
- [Changelog](https://github.com/ankane/chartkick/blob/master/CHANGELOG.md)
- [Commits](ankane/chartkick@v5.1.2...v5.1.3)

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

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

Gemfile.lock

@@ -91,7 +91,7 @@ GEM
       uniform_notifier (~> 1.11)
     byebug (11.1.3)
     cancancan (3.3.0)
-    chartkick (5.1.2)
+    chartkick (5.1.3)
     cocoon (1.2.15)
     coderay (1.1.3)
     coffee-rails (5.0.0)