Use pyproject.toml as single source of truth

Author: Cito

src/pytest_describe/__init__.py

@@ -1,5 +1,10 @@
+import importlib.metadata as metadata
+
 from .shared import behaves_like
 
 __all__ = ["behaves_like"]
 
-__version__ = "3.0.0a0"
+try:
+    __version__ = metadata.version("pytest-describe")
+except metadata.PackageNotFoundError:  # pragma: no cover
+    __version__ = "0+unknown"

test/test_metadata.py

@@ -0,0 +1,11 @@
+"""Test metadata"""
+
+import pytest_describe
+
+
+def test_version_is_set():
+    version = pytest_describe.__version__
+    assert isinstance(version, str)
+    assert "." in version
+    assert not version.startswith("0")
+    assert "unknown" not in version