Bump steep from 1.9.3 to 1.9.4

Bumps [steep](https://github.com/soutaro/steep) from 1.9.3 to 1.9.4.
- [Release notes](https://github.com/soutaro/steep/releases)
- [Changelog](https://github.com/soutaro/steep/blob/master/CHANGELOG.md)
- [Commits](soutaro/steep@v1.9.3...v1.9.4)

---
updated-dependencies:
- dependency-name: steep
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -128,7 +128,7 @@ GEM
     ruby-progressbar (1.13.0)
     securerandom (0.4.1)
     stackprof (0.2.27)
-    steep (1.9.3)
+    steep (1.9.4)
       activesupport (>= 5.1)
       concurrent-ruby (>= 1.1.10)
       csv (>= 3.0.9)