chore(librarian): update noxfile.py in generator-input (#1167)

This PR applies the patches from
#1156 and
#1163 to the
generated noxfile.py under `generator-input` here :
https://github.com/googleapis/python-firestore/blob/main/.librarian/generator-input/noxfile.py

Author: parthea

.librarian/generator-input/noxfile.py

@@ -71,6 +71,7 @@
 SYSTEM_TEST_EXTERNAL_DEPENDENCIES: List[str] = [
     "pytest-asyncio==0.21.2",
     "six",
+    "pyyaml",
 ]
 SYSTEM_TEST_LOCAL_DEPENDENCIES: List[str] = []
 SYSTEM_TEST_DEPENDENCIES: List[str] = []
@@ -80,7 +81,6 @@
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 
 nox.options.sessions = [
-    "unit-3.9",
     "unit-3.10",
     "unit-3.11",
     "unit-3.12",