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

@@ -178,7 +178,8 @@ GEM
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
     retriable (3.1.2)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rouge (2.0.7)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
@@ -191,6 +192,7 @@ GEM
     simctl (1.6.10)
       CFPropertyList
       naturally
+    strscan (3.1.0)
     terminal-notifier (2.0.0)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)