Bump rexml from 3.2.5 to 3.2.8

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] <support@github.com>

Gemfile.lock

@@ -14,7 +14,8 @@ GEM
     rainbow (3.0.0)
     rake (13.0.1)
     regexp_parser (2.1.1)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rubocop (1.20.0)
       parallel (~> 1.10)
       parser (>= 3.0.0.0)
@@ -33,6 +34,7 @@ GEM
     standard (1.3.0)
       rubocop (= 1.20.0)
       rubocop-performance (= 1.11.5)
+    strscan (3.1.0)
     unicode-display_width (2.1.0)
 
 PLATFORMS