chore: Add Python 3.13 updates for repo settings, noxfile, setup, constraints, .github (AI experiment) (#336)

* feat: Add Python 3.13 updates for repo settings and Kokoro

Includes additional updates for Python 3.13 support:

- Adds 'unit (3.13)' to the required status checks in the repo settings file (`.github/sync-repo-settings.yaml`).
- Populates and updates Kokoro sample configuration files in `.kokoro/samples/python3.13/` to mirror the 3.12 setup, adjusting version-specific variables.

* 🦉 Updates from OwlBot post-processor

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

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: 3 people

.github/sync-repo-settings.yaml

@@ -16,6 +16,7 @@ branchProtectionRules:
     - 'unit (3.10)'
     - 'unit (3.11)'
     - 'unit (3.12)'
+    - 'unit (3.13)'
     - 'cover'
 permissionRules:
   - team: actools-python

.github/workflows/unittest.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python: ['3.8', '3.9', '3.10', '3.11', '3.12']
+        python: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
     steps:
     - name: Checkout
       uses: actions/checkout@v4
@@ -39,7 +39,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ['3.12']
+        python: ['3.13']
     steps:
     - name: Checkout
       uses: actions/checkout@v4
@@ -67,7 +67,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ['3.12']
+        python: ['3.13']
     steps:
     - name: Checkout
       uses: actions/checkout@v4

noxfile.py

@@ -34,7 +34,15 @@
 
 DEFAULT_PYTHON_VERSION = "3.8"
 
-UNIT_TEST_PYTHON_VERSIONS: List[str] = ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+UNIT_TEST_PYTHON_VERSIONS: List[str] = [
+    "3.7",
+    "3.8",
+    "3.9",
+    "3.10",
+    "3.11",
+    "3.12",
+    "3.13",
+]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
     "asyncmock",

setup.py

@@ -69,6 +69,7 @@ def readme():
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.12",
+        "Programming Language :: Python :: 3.13",
         "Operating System :: OS Independent",
         "Topic :: Database :: Front-Ends",
     ],