test/run: Call ruff on Python executables

This spotted all errors fixed in the previous commits.

test/run

@@ -1,17 +1,16 @@
 #!/bin/sh
-
 set -eu
 
+PYEXEFILES="$(git grep -lI '^#!.*python') $(git ls-files "*.py")"
+
 test_ruff() {
     command -v ruff >/dev/null || { echo 'no ruff installed'; return 0; }
-    test -n "$(ruff check --show-files .)" || return 0  # no python changes
-    ruff check --no-cache .
+    ruff check --no-cache . $PYEXEFILES
 }
 
 test_ruff
 
 # run static code checks like pyflakes and pep8
-PYEXEFILES="$(git grep -lI '^#!.*python') $(git ls-files "*.py")"
 flake8 $PYEXEFILES
 
 ./test-bots