[pre-commit.ci] pre-commit autoupdate

updates:
- [github.com/astral-sh/ruff-pre-commit: v0.6.7 → v0.6.8](astral-sh/ruff-pre-commit@v0.6.7...v0.6.8)

Author: pre-commit-ci[bot]

.pre-commit-config.yaml

@@ -25,7 +25,7 @@ repos:
         exclude: &exclude_pattern 'iv_weak_instruments.ipynb'
         args: ["--maxkb=1500"]
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.6.7
+    rev: v0.6.8
     hooks:
       # Run the linter
       - id: ruff