Pins protobuf version <= 3.20.0 to satisfy both Vizier and TensorFlow requirements.

PiperOrigin-RevId: 534124782

Author: mihirparadkar

kokoro/github/ubuntu/cpu/oldest/continuous.cfg

@@ -6,7 +6,7 @@ env_vars: {
 }
 env_vars: {
   key: "TF_VERSION"
-  value: "2.12.*"
+  value: "2.9.*"
 }
 env_vars: {
   key: "TAG_FILTERS"

kokoro/github/ubuntu/cpu/oldest/presubmit.cfg

@@ -6,7 +6,7 @@ env_vars: {
 }
 env_vars: {
   key: "TF_VERSION"
-  value: "2.12.*"
+  value: "2.9.*"
 }
 env_vars: {
   key: "TAG_FILTERS"

setup.py

@@ -177,6 +177,9 @@ def get_version():
         'tensorflow>=2.9.0; platform_machine != "arm64" or platform_system != "Darwin"',
         'tensorflow-macos>=2.9.0; platform_machine == "arm64" and platform_system == "Darwin"',
         # pylint:enable=g-line-too-long
+        # TODO(b/283835852): Remove when Vizier can upgrade to protobuf >= 4.0.
+        'protobuf~=3.20.3',
+        'wrapt~=1.14.1',
     ],
     python_requires='>=3.8,<4',
     packages=find_namespace_packages(