Specify Python version for auto-formatters (#3325)

* chore(isort): specify Python version to be assumed

https://pycqa.github.io/isort/docs/configuration/options#python-version

Default is to assume _any_ Python 3 version could be the target.

* chore(black): specify Python target versions

https://black.readthedocs.io/en/stable/usage_and_configuration/the_basics.html#t-target-version

* chore(ruff): specify Python version to be assumed

https://docs.astral.sh/ruff/settings/#target-version

* chore: exclude directories from auto-formatting

.isort.cfg

@@ -1,4 +1,5 @@
 [settings]
+py_version=39
 known_first_party=anki,aqt,tests
 profile=black
 extend_skip=qt/bundle

.ruff.toml

@@ -0,0 +1,2 @@
+target-version = "py39"
+extend-exclude = ["qt/bundle"]

pyproject.toml

@@ -0,0 +1,3 @@
+[tool.black]
+target-version = ["py39", "py310", "py311", "py312"]
+extend-exclude = "qt/bundle"

qt/.isort.cfg

@@ -1,4 +1,5 @@
 [settings]
+py_version=39
 profile=black
 known_first_party=anki,aqt
 extend_skip=aqt/forms,hooks_gen.py