Update requirements.txt

python/requirements.txt

@@ -4,7 +4,7 @@ wheel>=0.34.0, <0.35.0
 setuptools>=44.1.0
 google>=2.0.3
 protobuf>=3.12.2
-grpcio-tools>=1.28.1
+grpcio-tools==1.33.2
 grpcio>=1.28.1
 func-timeout>=4.3.5
 pyyaml>=5.1