Bump power_assert from 2.0.3 to 2.0.4

Bumps [power_assert](https://github.com/ruby/power_assert) from 2.0.3 to 2.0.4.
- [Release notes](https://github.com/ruby/power_assert/releases)
- [Commits](ruby/power_assert@v2.0.3...v2.0.4)

---
updated-dependencies:
- dependency-name: power_assert
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -70,7 +70,7 @@ GEM
     parser (3.3.6.0)
       ast (~> 2.4.1)
       racc
-    power_assert (2.0.3)
+    power_assert (2.0.4)
     psych (4.0.6)
       stringio
     public_suffix (6.0.1)