ruff: remove deprecated setting

WhyNotHugo · WhyNotHugo · commit 687324950e03 · 2025-08-27T12:59:30.000+02:00
Ruff now uses the value from requires-python.
diff --git a/pyproject.toml b/pyproject.toml
@@ -81,7 +81,6 @@ select = [
     "PLE",
     "RUF",
 ]
-target-version = "py39"
 
 [tool.ruff.isort]
 force-single-line = true
