Bump stackprof from 0.2.20 to 0.2.21 (#19027)

Bumps [stackprof](https://github.com/tmm1/stackprof) from 0.2.20 to 0.2.21.
- [Release notes](https://github.com/tmm1/stackprof/releases)
- [Changelog](https://github.com/tmm1/stackprof/blob/master/CHANGELOG.md)
- [Commits](https://github.com/tmm1/stackprof/compare/v0.2.20...v0.2.21

)

---
updated-dependencies:
- dependency-name: stackprof
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -648,7 +648,7 @@ GEM
     sshkit (1.21.2)
       net-scp (>= 1.1.2)
       net-ssh (>= 2.8.0)
-    stackprof (0.2.20)
+    stackprof (0.2.21)
     statsd-ruby (1.5.0)
     stoplight (3.0.0)
     strong_migrations (0.7.9)