chore: allow 3.9 unittest to avoid CI/CD fail

Author: chalmerlowe

packages/bigframes/noxfile.py

@@ -54,7 +54,7 @@
 
 DEFAULT_PYTHON_VERSION = "3.14"
 
-ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14"]
+ALL_PYTHON = ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
     PYTEST_VERSION,