Update quickstart samples for python 3.14 (#13672)

* Update quickstart samples for python 3.14

* Update pytest

* Update pytest to be a working version for both 3.9, 3.14

---------

Co-authored-by: Katie McLaughlin <katie@glasnt.com>
Co-authored-by: Katie McLaughlin <glasnt@google.com>

Author: ShellyAgg

appengine/flexible/hello_world/app.yaml

@@ -17,7 +17,7 @@ env: flex
 entrypoint: gunicorn -b :$PORT main:app
 
 runtime_config:
-  operating_system: ubuntu22
+  operating_system: ubuntu24
 
 # This sample incurs costs to run on the App Engine flexible environment.
 # The settings below are to reduce costs during testing and are not appropriate

appengine/standard_python3/building-an-app/building-an-app-1/app.yaml

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-runtime: python313
+runtime: python314
 
 handlers:
   # This configures Google App Engine to serve the files in the app's static

appengine/standard_python3/building-an-app/building-an-app-1/requirements-test.txt

@@ -1 +1,2 @@
-pytest==7.0.1
+pytest==7.0.1; python_version == '3.9'
+pytest==9.0.2; python_version >= '3.10'