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>

Author: dependabot[bot]

Gemfile.lock

@@ -417,7 +417,8 @@ GEM
       io-console (~> 0.5)
     request_store (1.5.1)
       rack (>= 1.4)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rspec-core (3.13.0)
       rspec-support (~> 3.13.0)
     rspec-expectations (3.13.0)
@@ -484,6 +485,7 @@ GEM
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
     stringio (3.1.0)
+    strscan (3.1.0)
     sxp (2.0.0)
       matrix (~> 0.4)
       rdf (~> 3.3)