Bump stringio from 3.1.2 to 3.1.5

Bumps [stringio](https://github.com/ruby/stringio) from 3.1.2 to 3.1.5.
- [Release notes](https://github.com/ruby/stringio/releases)
- [Changelog](https://github.com/ruby/stringio/blob/master/NEWS.md)
- [Commits](ruby/stringio@v3.1.2...v3.1.5)

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

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -88,7 +88,7 @@ GEM
       strscan (>= 1.0.0)
       terminal-table (>= 2, < 4)
       uri (>= 0.12.0)
-    stringio (3.1.2)
+    stringio (3.1.5)
     strscan (3.1.2)
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)