Bump rexml from 3.3.8 to 3.3.9 in the bundler group

Bumps the bundler group with 1 update: [rexml](https://github.com/ruby/rexml).


Updates `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
  dependency-group: bundler
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -408,7 +408,7 @@ GEM
     responders (3.1.1)
       actionpack (>= 5.2)
       railties (>= 5.2)
-    rexml (3.3.8)
+    rexml (3.3.9)
     rouge (4.4.0)
     rqrcode (2.2.0)
       chunky_png (~> 1.0)