Bump rexml from 3.2.6 to 3.2.8 (#1537)

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

Gemfile.lock

@@ -577,7 +577,8 @@ GEM
     request_store (1.6.0)
       rack (>= 1.4)
     retriable (3.1.2)
-    rexml (3.2.6)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rinku (2.0.6)
     roadie (5.2.1)
       css_parser (~> 1.4)
@@ -732,6 +733,7 @@ GEM
       http_signatures (~> 0)
       jwt (~> 2.1, >= 2.1.0)
     stripe (5.55.0)
+    strscan (3.1.0)
     thor (1.3.1)
     tilt (2.3.0)
     timecop (0.9.8)