chore(deps): bump rexml from 3.3.7 to 3.3.9 in /example (#676)

Bumps [rexml](https://github.com/ruby/rexml) from 3.3.7 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@v3.3.7...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]

Diff for: example/Gemfile.lock

@@ -70,6 +70,7 @@ GEM
     ethon (0.16.0)
       ffi (>= 1.15.0)
     ffi (1.17.0-arm64-darwin)
+    ffi (1.17.0-x86_64-linux-gnu)
     fourflusher (2.3.1)
     fuzzy_match (2.0.4)
     gh_inspector (1.1.3)
@@ -85,7 +86,7 @@ GEM
     netrc (0.11.0)
     nkf (0.2.0)
     public_suffix (4.0.7)
-    rexml (3.3.7)
+    rexml (3.3.9)
     ruby-macho (2.5.1)
     ruby2_keywords (0.0.5)
     typhoeus (1.4.1)
@@ -102,6 +103,7 @@ GEM
 
 PLATFORMS
   arm64-darwin
+  x86_64-linux
 
 DEPENDENCIES
   activesupport (>= 6.1.7.5, != 7.1.0)