⬆️ Bump rexml from 3.3.8 to 3.3.9

Bumps [rexml](https://github.com/ruby/rexml) from 3.3.8 to 3.3.9.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.3.8...v3.3.9)

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

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

Gemfile.lock

@@ -345,7 +345,7 @@ GEM
     regexp_parser (2.9.2)
     request_store (1.7.0)
       rack (>= 1.4)
-    rexml (3.3.8)
+    rexml (3.3.9)
     rollbar (3.6.0)
     rspec (3.13.0)
       rspec-core (~> 3.13.0)