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

@@ -184,7 +184,8 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     roar (1.1.1)
       representable (~> 3.0)
     rspec (3.9.0)
@@ -250,6 +251,7 @@ GEM
       dante (>= 0.2.0)
       multi_json (~> 1.0)
       stripe (>= 1.31.0, <= 1.58.0)
+    strscan (3.1.0)
     timecop (0.9.1)
     timers (4.3.5)
     trailblazer-option (0.1.2)