Assorted fixes (#25)

* Updated imports for Netbox 3.6.1

Closes #21 and #23

* Changed Fieldtypes of Start and Expiration Date

Closes #22

* Bump to NetBox v3.6.1

* Add pyproject.toml and python workflow

---------

Co-authored-by: Manuel Hartung <manuel.hartung@atos.net>

pyproject.toml

@@ -0,0 +1,73 @@
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "netbox-slm"
+dynamic = ["version"]
+description = "Software Lifecycle Management Netbox Plugin"
+readme = "README.md"
+requires-python = ">=3.9"
+license = { text = "Apache-2.0" }
+authors = [
+    {name = "ICTU", email = "open-source-projects@ictu.nl"},
+]
+classifiers = [
+    "Environment :: Web Environment",
+    "Framework :: Django",
+    "Intended Audience :: Developers",
+    "License :: OSI Approved :: Apache Software License",
+    "Operating System :: OS Independent",
+    "Programming Language :: Python",
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3 :: Only",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Topic :: Internet :: WWW/HTTP",
+    "Topic :: Internet :: WWW/HTTP :: Dynamic Content",
+]
+dependencies = []
+
+[project.optional-dependencies]
+build = [
+    "build == 1.0.3",
+    "setuptools == 68.2.0",
+    "twine == 3.7.1",
+]
+tools = [
+    "black == 23.3.0",
+    "ruff == 0.0.275",
+]
+
+[tool.setuptools.dynamic]
+version = {attr = "netbox_slm.__version__"}
+
+[tool.setuptools.packages.find]
+include = ["netbox_slm"]
+
+[tool.black]
+line-length = 120
+target-version = ["py39"]
+color = true
+check = true
+diff = true
+fast = true
+extend-exclude = '''
+netbox_slm/migrations/.*.py
+'''
+
+[tool.ruff]
+line-length = 120
+target-version = "py39"
+format = "github"
+src = ["netbox_slm"]
+
+[tool.ruff.per-file-ignores]
+"__init__.py" = [
+    "D104",  # https://beta.ruff.rs/docs/rules/#pydocstyle-d - don't require doc strings in __init__.py files
+    "F401",  # https://beta.ruff.rs/docs/rules/#pyflakes-f - don't complain about unused imports in __init__.py files
+]
+"netbox_slm/migrations/*.py" = [
+    "E501",  # https://beta.ruff.rs/docs/rules/line-too-long/ - don't check on Django generated migration files
+]