Bump stringio from 3.1.5 to 3.1.6

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]>

Author: dependabot[bot]

Gemfile.lock

@@ -154,7 +154,7 @@ GEM
       strscan (>= 1.0.0)
       terminal-table (>= 2, < 5)
       uri (>= 0.12.0)
-    stringio (3.1.5)
+    stringio (3.1.6)
     strong_json (2.1.2)
     strscan (3.1.2)
     tempfile (0.3.1)