Bump rexml from 3.2.6 to 3.2.8

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.6 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@v3.2.6...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 (3.1.1)
     rake (13.1.0)
     regexp_parser (2.9.0)
-    rexml (3.2.6)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rghost (0.9.8)
     rghost_barcode (0.9)
     rspec (3.12.0)
@@ -81,6 +82,7 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.4)
+    strscan (3.1.0)
     test-prof (1.3.1)
     timecop (0.9.8)
     unicode-display_width (2.5.0)