infra: bump ruff from 0.6.7 to 0.6.8 in /dockerfile

Bumps [ruff](https://github.com/astral-sh/ruff) from 0.6.7 to 0.6.8.
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.6.7...0.6.8)

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

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

dockerfile/anaconda-ci/requirements.txt

@@ -19,7 +19,7 @@ pylint == 3.3.0
 astroid == 3.3.4
 
 # ruff for fast linting
-ruff == 0.6.7
+ruff == 0.6.8
 
 # vulture for dead code analysis
 vulture == 2.12