build(deps): bump docker-api from 2.3.0 to 2.4.0

Bumps [docker-api](https://github.com/swipely/docker-api) from 2.3.0 to 2.4.0.
- [Release notes](https://github.com/swipely/docker-api/releases)
- [Commits](upserve/docker-api@v2.3.0...v2.4.0)

---
updated-dependencies:
- dependency-name: docker-api
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -4,10 +4,10 @@ GEM
     base64 (0.2.0)
     coderay (1.1.3)
     diff-lcs (1.5.1)
-    docker-api (2.3.0)
+    docker-api (2.4.0)
       excon (>= 0.64.0)
       multi_json
-    excon (0.112.0)
+    excon (1.2.1)
     method_source (1.1.0)
     multi_json (1.15.0)
     net-scp (4.0.0)