tools: ynl: add initial pyproject.toml for packaging

Add pyproject.toml and define authors, dependencies and
user-facing scripts. This will be used later by pip to
install python code.

Signed-off-by: Jan Stancek <[e-mail]>
Reviewed-by: Donald Hunter <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/net/ynl/pyproject.toml

···
+[build-system]
+requires = ["setuptools>=61.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "pyynl"
+authors = [
+    {name = "Donald Hunter", email = "[e-mail]"},
+    {name = "Jakub Kicinski", email = "[e-mail]"},
+]
+description = "yaml netlink (ynl)"
+version = "0.0.1"
+requires-python = ">=3.9"
+dependencies = [
+    "pyyaml==6.*",
+    "jsonschema==4.*"
+]
+
+[tool.setuptools.packages.find]
+include = ["pyynl", "pyynl.lib"]
+
+[project.scripts]
+ynl = "pyynl.cli:main"
+ynl-ethtool = "pyynl.ethtool:main"