Bump puma from 5.6.7 to 5.6.8

Bumps [puma](https://github.com/puma/puma) from 5.6.7 to 5.6.8.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v5.6.7...v5.6.8)

---
updated-dependencies:
- dependency-name: puma
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -4,8 +4,8 @@ GEM
     diff-lcs (1.3)
     knapsack (1.14.0)
       rake
-    nio4r (2.5.9)
-    puma (5.6.7)
+    nio4r (2.7.0)
+    puma (5.6.8)
       nio4r (~> 2.0)
     rake (13.0.1)
     rspec (3.6.0)