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]>

Author: dependabot[bot]

Gemfile.lock

@@ -371,7 +371,8 @@ GEM
     retriable (3.1.2)
     reverse_markdown (2.1.1)
       nokogiri
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rspec-core (3.12.2)
       rspec-support (~> 3.12.0)
     rspec-expectations (3.12.3)
@@ -458,6 +459,7 @@ GEM
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
     stackprof (0.2.25)
+    strscan (3.1.0)
     temple (0.10.2)
     thor (1.3.1)
     tilt (2.2.0)