utils/check-package: add inline script requirements

The check-package tool requires some PyPi package to be installed before
it can run. This is typically done by manually installing them into the
user's global Python environment or setting up a virtual environment,
then manually installing each dependency.

Python recently defined a format for managing script dependencies as
inline metadata[1]. This can be used with the `uv` tool to run a Python
script and automatically install the minimum required version of Python
and PyPi dependencies.

With this change, it's now possible to run check-package with

  uv run -s ./utils/check-package

Note that, because check-package does not have the '.py' file extension
we must specify the `-s` or `--script` argument. That argument was added
very recently in release 0.4.19[2].

I set the minimum python to 3.9 as that is the oldest version still
supported[3]. I verified 3.9 works by running

  uv run -p 3.9 -s ./utils/check-package `git ls-tree -r --name-only HEAD` --ignore-list=.checkpackageignore

[1] https://packaging.python.org/en/latest/specifications/inline-script-metadata/#script-type
[2] https://github.com/astral-sh/uv/releases/tag/0.4.19
[3] https://devguide.python.org/versions/

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 6ffcdb52e80b63e68c890aed52ff7f4d00e079b8)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

utils/check-package

@@ -1,5 +1,12 @@
 #!/usr/bin/env python3
 # See utils/checkpackagelib/readme.txt before editing this file.
+# /// script
+# requires-python = ">=3.9"
+# dependencies = [
+#     "flake8",
+#     "python-magic",
+# ]
+# ///
 
 import argparse
 import inspect