Bump chartkick from 3.3.2 to 3.4.0

Bumps [chartkick](https://github.com/ankane/chartkick) from 3.3.2 to 3.4.0.
- [Release notes](https://github.com/ankane/chartkick/releases)
- [Changelog](https://github.com/ankane/chartkick/blob/master/CHANGELOG.md)
- [Commits](ankane/chartkick@v3.3.2...v3.4.0)

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

Author: dependabot-preview[bot]

Gemfile.lock

@@ -120,7 +120,7 @@ GEM
     capybara-screenshot (1.0.24)
       capybara (>= 1.0, < 4)
       launchy
-    chartkick (3.3.2)
+    chartkick (3.4.0)
     childprocess (3.0.0)
     choice (0.2.0)
     climate_control (0.2.0)