build(deps): bump ruff from 0.15.4 to 0.15.8 (#72)

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

Author: dependabot[bot]

requirements.txt

@@ -1,3 +1,3 @@
 slack-bolt==1.27.0
 pytest==9.0.2
-ruff==0.15.4
+ruff==0.15.8