Bump stringio from 3.1.5 to 3.1.6 (#2806)

Bumps [stringio](https://github.com/ruby/stringio) from 3.1.5 to 3.1.6.
- [Release notes](https://github.com/ruby/stringio/releases)
- [Changelog](https://github.com/ruby/stringio/blob/master/NEWS.md)
- [Commits](ruby/stringio@v3.1.5...v3.1.6)

---
updated-dependencies:
- dependency-name: stringio
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -390,7 +390,7 @@ GEM
     simplecov_json_formatter (0.1.4)
     stimulus-rails (1.3.4)
       railties (>= 6.0.0)
-    stringio (3.1.5)
+    stringio (3.1.6)
     thor (1.3.2)
     timeout (0.4.3)
     turbo-rails (2.0.13)