chore: adds Python 3.7/3.8 EOL pending deprecation warning (#1123)

* Adds deprecation warning regarding Python 3.7 3.8

* removes no warnings plugin and tweaks settings

* 🦉 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: Lingqing Gan <[email protected]>

Author: 3 people

setup.cfg

@@ -23,5 +23,5 @@ requirement_cls=sqlalchemy_bigquery.requirements:Requirements
 profile_file=.sqlalchemy_dialect_compliance-profiles.txt
 
 [tool:pytest]
-addopts= --tb native -v -r fxX -p no:warnings
+addopts= --tb native -v -r fxX
 python_files=tests/*test_*.py

sqlalchemy_bigquery/__init__.py

@@ -20,6 +20,8 @@
 SQLAlchemy dialect for Google BigQuery
 """
 
+import warnings
+
 from .version import __version__
 
 from .base import BigQueryDialect, dialect
@@ -43,6 +45,20 @@
     TIMESTAMP,
 )
 
+from . import _versions_helpers
+
+sys_major, sys_minor, sys_micro = _versions_helpers.extract_runtime_version()
+if sys_major == 3 and sys_minor in (7, 8):
+    warnings.warn(
+        "The python-bigquery library will stop supporting Python 3.7 "
+        "and Python 3.8 in a future major release expected in Q4 2024. "
+        f"Your Python version is {sys_major}.{sys_minor}.{sys_micro}. We "
+        "recommend that you update soon to ensure ongoing support. For "
+        "more details, see: [Google Cloud Client Libraries Supported Python Versions policy](https://cloud.google.com/python/docs/supported-python-versions)",
+        PendingDeprecationWarning,
+    )
+
+
 __all__ = [
     "__version__",
     "dialect",

sqlalchemy_bigquery/_versions_helpers.py

@@ -0,0 +1,32 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Shared helper functions for verifying versions of installed modules."""
+
+
+import sys
+from typing import Tuple
+
+
+def extract_runtime_version() -> Tuple[int, int, int]:
+    # Retrieve the version information
+    version_info = sys.version_info
+
+    # Extract the major, minor, and micro components
+    major = version_info.major
+    minor = version_info.minor
+    micro = version_info.micro
+
+    # Display the version number in a clear format
+    return major, minor, micro