Bump rexml from 3.2.5 to 3.3.6 in /src/supermarket/engines/fieri

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.5 to 3.3.6.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.5...v3.3.6)

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

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

src/supermarket/engines/fieri/Gemfile.lock

@@ -186,7 +186,8 @@ GEM
     rake (13.0.6)
     redis (4.6.0)
     regexp_parser (2.5.0)
-    rexml (3.2.5)
+    rexml (3.3.6)
+      strscan
     rspec-core (3.11.0)
       rspec-support (~> 3.11.0)
     rspec-expectations (3.11.1)