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](https://github.com/ruby/rexml/compare/v3.2.6...v3.2.8)

---
updated-dependencies:
- dependency-name: rexml
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -150,7 +150,8 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    rexml (3.2.6)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rqrcode_core (1.2.0)
     rr (3.1.0)
     rspec (3.13.0)
@@ -199,6 +200,7 @@ GEM
     sqlite3 (1.7.3-arm64-darwin)
     sqlite3 (1.7.3-x86_64-linux)
     stringio (3.1.0)
+    strscan (3.1.0)
     sync (0.5.0)
     term-ansicolor (1.8.0)
       tins (~> 1.0)