build: drop support for Python 3.9

Author: aseering

.github/workflows/presubmit.yaml

@@ -27,7 +27,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+        python: ["3.10", "3.11", "3.12", "3.13", "3.14"]
 
     steps:
       - name: Checkout code

.kokoro/presubmit/integration-regular-sessions-enabled.cfg

@@ -3,7 +3,7 @@
 # Only run a subset of all nox sessions
 env_vars: {
     key: "NOX_SESSION"
-    value: "unit-3.9 unit-3.14 system-3.14"
+    value: "unit-3.14 system-3.14"
 }
 
 env_vars: {

.kokoro/presubmit/presubmit.cfg

@@ -3,5 +3,5 @@
 # Only run a subset of all nox sessions
 env_vars: {
     key: "NOX_SESSION"
-    value: "unit-3.9 unit-3.12 cover docs docfx"
+    value: "unit-3.12 cover docs docfx"
 }

.kokoro/test-samples-impl.sh

@@ -35,7 +35,7 @@ export PYTHONUNBUFFERED=1
 env | grep KOKORO
 
 # Install nox
-python3.9 -m pip install --upgrade --quiet nox
+python3.10 -m pip install --upgrade --quiet nox
 
 # Use secrets acessor service account to get secrets
 if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
@@ -88,7 +88,7 @@ for file in samples/**/requirements.txt; do
     echo "------------------------------------------------------------"
 
     # Use nox to execute the tests for the project.
-    python3.9 -m nox -s "$RUN_TESTS_SESSION"
+    python3.10 -m nox -s "$RUN_TESTS_SESSION"
     EXIT=$?
 
     # If this is a periodic build, send the test log to the FlakyBot.

noxfile.py

@@ -42,7 +42,6 @@
 SYSTEM_TEST_PYTHON_VERSIONS: List[str] = ["3.14"]
 
 UNIT_TEST_PYTHON_VERSIONS: List[str] = [
-    "3.9",
     "3.10",
     "3.11",
     "3.12",
@@ -81,7 +80,6 @@
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 
 nox.options.sessions = [
-    "unit-3.9",
     "unit-3.10",
     "unit-3.11",
     "unit-3.12",

setup.py

@@ -87,7 +87,6 @@
         "License :: OSI Approved :: Apache Software License",
         "Programming Language :: Python",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.12",
@@ -99,7 +98,7 @@
     packages=packages,
     install_requires=dependencies,
     extras_require=extras,
-    python_requires=">=3.9",
+    python_requires=">=3.10",
     include_package_data=True,
     zip_safe=False,
 )