Bump logger from 1.6.3 to 1.6.4

Bumps [logger](https://github.com/ruby/logger) from 1.6.3 to 1.6.4.
- [Release notes](https://github.com/ruby/logger/releases)
- [Commits](ruby/logger@v1.6.3...v1.6.4)

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

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

Gemfile.lock

@@ -160,7 +160,7 @@ GEM
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
     json (2.9.0)
-    logger (1.6.3)
+    logger (1.6.4)
     loofah (2.23.1)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)