Add unit tests for authentication and webhook parsing

- Implement tests for basic and bearer authentication headers in `test_auth.py`.
- Create tests for the `EasybillWebhookParser` in `test_webhooks.py`, covering JSON and form-encoded payloads, as well as a generic parse and acknowledgement method.

generated/sync/pyproject.toml

@@ -0,0 +1,94 @@
+[project]
+name = "easybill_generated_sync"
+version = "1.0.0"
+description = "easybill REST API"
+authors = [
+  {name = "OpenAPI Generator Community",email = "team@openapitools.org"},
+]
+readme = "README.md"
+keywords = ["OpenAPI", "OpenAPI-Generator", "easybill REST API"]
+requires-python = ">=3.9"
+
+dependencies = [
+  "python-dateutil (>=2.8.2)",
+  "httpx (>=0.28.1)",
+  "pydantic (>=2.11)",
+  "typing-extensions (>=4.7.1)",
+]
+
+[project.urls]
+Repository = "https://github.com/GIT_USER_ID/GIT_REPO_ID"
+
+[tool.poetry]
+requires-poetry = ">=2.0"
+
+[tool.poetry.group.dev.dependencies]
+pytest = ">= 7.2.1"
+pytest-cov = ">= 2.8.1"
+tox = ">= 3.9.0"
+flake8 = ">= 4.0.0"
+types-python-dateutil = ">= 2.8.19.14"
+mypy = ">= 1.5"
+
+
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[tool.pylint.'MESSAGES CONTROL']
+extension-pkg-whitelist = "pydantic"
+
+[tool.mypy]
+files = [
+  "easybill_generated_sync",
+  #"test",  # auto-generated tests
+  "tests", # hand-written tests
+]
+# TODO: enable "strict" once all these individual checks are passing
+# strict = true
+
+# List from: https://mypy.readthedocs.io/en/stable/existing_code.html#introduce-stricter-options
+warn_unused_configs = true
+warn_redundant_casts = true
+warn_unused_ignores = true
+
+## Getting these passing should be easy
+strict_equality = true
+extra_checks = true
+
+## Strongly recommend enabling this one as soon as you can
+check_untyped_defs = true
+
+## These shouldn't be too much additional work, but may be tricky to
+## get passing if you use a lot of untyped libraries
+disallow_subclassing_any = true
+disallow_untyped_decorators = true
+disallow_any_generics = true
+
+### These next few are various gradations of forcing use of type annotations
+#disallow_untyped_calls = true
+#disallow_incomplete_defs = true
+#disallow_untyped_defs = true
+#
+### This one isn't too hard to get passing, but return on investment is lower
+#no_implicit_reexport = true
+#
+### This one can be tricky to get passing if you use a lot of untyped libraries
+#warn_return_any = true
+
+[[tool.mypy.overrides]]
+module = [
+  "easybill_generated_sync.configuration",
+]
+warn_unused_ignores = true
+strict_equality = true
+extra_checks = true
+check_untyped_defs = true
+disallow_subclassing_any = true
+disallow_untyped_decorators = true
+disallow_any_generics = true
+disallow_untyped_calls = true
+disallow_incomplete_defs = true
+disallow_untyped_defs = true
+no_implicit_reexport = true
+warn_return_any = true