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] <[email protected]>

Gemfile.lock

@@ -32,7 +32,8 @@ GEM
     rainbow (3.0.0)
     rake (13.0.3)
     regexp_parser (2.0.3)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rubocop (1.7.0)
       parallel (~> 1.10)
       parser (>= 2.7.1.5)
@@ -55,6 +56,8 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.3)
+    strscan (3.1.0)
+    strscan (3.1.0-java)
     unicode-display_width (1.7.0)
     wavefile (0.6.0)