Bump rexml from 3.3.8 to 3.3.9 in /packaging/fpm (#5612)

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
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

packaging/fpm/Gemfile.lock

@@ -23,7 +23,7 @@ GEM
       insist
       mustache (= 0.99.8)
       stud
-    rexml (3.3.8)
+    rexml (3.3.9)
     stud (0.0.23)
 
 PLATFORMS