Bump rexml from 3.2.5 to 3.2.8 in /test_app

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.5 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@v3.2.5...v3.2.8)

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

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

test_app/Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: ..
   specs:
-    administrate-field-active_storage (0.4.1)
+    administrate-field-active_storage (1.0.2)
       administrate (>= 0.2.2)
       rails (>= 7.0)
 
@@ -229,7 +229,8 @@ GEM
     regexp_parser (2.2.0)
     reline (0.4.0)
       io-console (~> 0.5)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     ruby-vips (2.2.0)
       ffi (~> 1.12)
     ruby2_keywords (0.0.5)
@@ -258,6 +259,7 @@ GEM
       sprockets (>= 3.0.0)
     sqlite3 (1.4.2)
     stringio (3.0.9)
+    strscan (3.1.0)
     thor (1.3.0)
     tilt (2.0.10)
     timeout (0.4.1)