testenv: bump grpcio to 1.68.1

Author: Yaroslav Leonov

test-requirements-proto5.txt

@@ -11,7 +11,7 @@ docker==5.0.0
 docker-compose==1.29.2
 dockerpty==0.4.1
 docopt==0.6.2
-grpcio==1.64.0
+grpcio==1.68.1
 idna==3.2
 importlib-metadata==4.6.1
 iniconfig==1.1.1