Bump toml-rb from 2.2.0 to 4.0.0 (heroku#1570)

Bumps [toml-rb](https://github.com/emancu/toml-rb) from 2.2.0 to 4.0.0.
- [Release notes](https://github.com/emancu/toml-rb/releases)
- [Commits](emancu/toml-rb@v2.2.0...v4.0.0)

---
updated-dependencies:
- dependency-name: toml-rb
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -34,6 +34,7 @@ GEM
       heroics (~> 0.1.1)
       moneta (~> 1.0.0)
       rate_throttle_client (~> 0.1.0)
+    racc (1.8.1)
     rake (13.2.1)
     rate_throttle_client (0.1.2)
     redis (5.3.0)
@@ -51,8 +52,9 @@ GEM
     rspec-support (3.13.1)
     thor (1.3.1)
     threaded (0.0.4)
-    toml-rb (2.2.0)
+    toml-rb (4.0.0)
       citrus (~> 3.0, > 3.0)
+      racc (~> 1.7)
     webrick (1.8.2)
 
 PLATFORMS