Bump rexml in /fixture in the bundler group across 1 directory

Bumps the bundler group with 1 update in the /fixture directory: [rexml](https://github.com/ruby/rexml).


Updates `rexml` from 3.2.6 to 3.2.8
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.6...v3.2.8)

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

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

fixture/Gemfile.lock

@@ -86,8 +86,10 @@ GEM
     netrc (0.11.0)
     nkf (0.2.0)
     public_suffix (4.0.7)
-    rexml (3.2.6)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     ruby-macho (2.5.1)
+    strscan (3.1.0)
     typhoeus (1.4.1)
       ethon (>= 0.9.0)
     tzinfo (2.0.6)
@@ -102,6 +104,7 @@ GEM
 
 PLATFORMS
   arm64-darwin-23
+  x86_64-linux
 
 DEPENDENCIES
   cocoapods (~> 1.14.3)