Bump rexml from 3.2.8 to 3.2.9

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.8 to 3.2.9.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.8...v3.2.9)

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

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -558,8 +558,8 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    rexml (3.2.8)
-      strscan (>= 3.0.9)
+    rexml (3.2.9)
+      strscan
     rollbar (3.5.2)
     rspec-activejob (0.6.1)
       activejob (>= 4.2)