run pre-commit on all files (#1789)

pre-commit.ci has been disabled for a while.
This PR ensures that all the files has been validated/formatted by pre-commit, to avoid spurious diffs in subsequent PRs.

During the process, ruff broke the code because it removed an "unused" import which was actually used.
A linter which breaks my code is a linter which I cannot trust, so I just removed it. I re-enabled isort instead.

pyscript.core/test/pydom.py

@@ -1,8 +1,9 @@
 import random
+from datetime import datetime as dt
+
 from pyscript import display
 from pyweb import pydom
 from pyweb.base import when
-from datetime import datetime as dt
 
 
 @when("click", "#just-a-button")