Bump rexml from 3.2.6 to 3.2.8 in /gemfiles/rails_61 (#593)

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
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

gemfiles/rails_61/Gemfile.lock

@@ -168,7 +168,8 @@ GEM
       thor (~> 1.0)
     rake (13.2.1)
     regexp_parser (2.9.0)
-    rexml (3.2.6)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rspec (3.13.0)
       rspec-core (~> 3.13.0)
       rspec-expectations (~> 3.13.0)
@@ -208,6 +209,8 @@ GEM
       actionpack (>= 5.2)
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
+    strscan (3.1.0)
+    strscan (3.1.0-java)
     thor (1.3.1)
     timeout (0.4.1)
     tzinfo (2.0.6)