move extended rules to post-format check

Makefile

@@ -17,6 +17,8 @@ reformat:
 	ruff check --select F401,I --fix
 	# reformat
 	ruff format
+	# make an extended check with rules that might be triggered by reformat
+	ruff check --config ruff-extended.toml
 
 lint:
 	ruff check

ruff-extended.toml

@@ -0,0 +1,6 @@
+extend = "./ruff.toml"
+
+[lint]
+# Some rules are marked as incompatible with the formatter so use them in an extended check instead.
+# See: https://docs.astral.sh/ruff/formatter/#conflicting-lint-rules
+extend-select = ["E501", "ISC"]

ruff.toml

@@ -5,4 +5,4 @@ target-version = "py310"
 [lint]
 select = ["E", "F", "W", "I", "ASYNC", "UP", "FLY", "PERF", "FURB"]
 
-ignore = []
+ignore = ["E501"]