Bump rexml from 3.2.5 to 3.3.9 in /.github/workflows

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.5 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@v3.2.5...v3.3.9)

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

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

Author: dependabot[bot]

.github/workflows/Gemfile.lock

@@ -213,6 +213,8 @@ GEM
     minitest (5.16.2)
     nokogiri (1.13.8-arm64-darwin)
       racc (~> 1.4)
+    nokogiri (1.13.8-x86_64-linux)
+      racc (~> 1.4)
     octokit (4.25.1)
       faraday (>= 1, < 3)
       sawyer (~> 0.9)
@@ -223,7 +225,7 @@ GEM
     rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.5)
+    rexml (3.3.9)
     rouge (3.26.0)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
@@ -254,6 +256,7 @@ GEM
 
 PLATFORMS
   arm64-darwin-20
+  x86_64-linux
 
 DEPENDENCIES
   commonmarker (~> 0.23)