fix: move version module to django_spanner.version (#844)

* fix: move version module to

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Knut Olav Løite <[email protected]>

Author: 3 people

django_spanner/__init__.py

@@ -27,6 +27,7 @@
 from .functions import register_functions
 from .lookups import register_lookups
 from .utils import check_django_compatability
+from .version import __version__
 
 # Monkey-patch google.DatetimeWithNanoseconds's __eq__ compare against
 # datetime.datetime.
@@ -47,8 +48,6 @@
 )
 from django.db.models import JSONField
 
-__version__ = pkg_resources.get_distribution("django-google-spanner").version
-
 USE_EMULATOR = os.getenv("SPANNER_EMULATOR_HOST") is not None
 
 # Only active LTS django versions (3.2.*, 4.2.*) are supported by this library right now.

version.py renamed to django_spanner/version.py

@@ -6,6 +6,7 @@
 
 import io
 import os
+import re
 
 from setuptools import find_packages, setup
 
@@ -27,16 +28,18 @@
 }
 
 BASE_DIR = os.path.dirname(__file__)
-VERSION_FILENAME = os.path.join(BASE_DIR, "version.py")
-PACKAGE_INFO = {}
-with open(VERSION_FILENAME) as f:
-    exec(f.read(), PACKAGE_INFO)
-version = PACKAGE_INFO["__version__"]
-
-# Setup boilerplate below this line.
 
 package_root = os.path.abspath(BASE_DIR)
 
+version = None
+
+with open(os.path.join(package_root, "django_spanner/version.py")) as fp:
+    version_candidates = re.findall(r"(?<=\")\d+.\d+.\d+(?=\")", fp.read())
+    assert len(version_candidates) == 1
+    version = version_candidates[0]
+
+# Setup boilerplate below this line.
+
 readme_filename = os.path.join(package_root, "README.rst")
 with io.open(readme_filename, encoding="utf-8") as readme_file:
     readme = readme_file.read()