Bump rexml from 3.3.0 to 3.3.9

Bumps [rexml](https://github.com/ruby/rexml) from 3.3.0 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@v3.3.0...v3.3.9)

---
updated-dependencies:
- dependency-name: rexml
  dependency-type: indirect
...

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

Gemfile.lock

@@ -269,8 +269,7 @@ GEM
     regexp_parser (2.9.2)
     reline (0.5.9)
       io-console (~> 0.5)
-    rexml (3.3.0)
-      strscan
+    rexml (3.3.9)
     rolify (6.0.1)
     rspec-core (3.13.2)
       rspec-support (~> 3.13.0)
@@ -364,7 +363,6 @@ GEM
     stimulus-rails (1.2.1)
       railties (>= 6.0.0)
     stringio (3.1.1)
-    strscan (3.1.0)
     thor (1.3.1)
     timeliness (0.5.0)
     timeout (0.4.1)