bump versions of grpcio and protobuf

[robertcsapo]

suggestion, to upgrade requirements.txt packages of grpcio and protobuf

grpcio==1.36.1
protobuf==3.15.6

why?

add support for python 3.9+

tested locally

git clone https://github.com/cisco-ie/ios-xr-grpc-python.git
(modify requirements.txt)
pip3 install -e .

Defaulting to user installation because normal site-packages is not writeable
Obtaining file:///workspaces/cisco-devnet-quiz/classroom/solved/model-driven_programmability_stack/grpc/ios-xr-grpc-python
Collecting grpcio==1.36.1
  Using cached grpcio-1.36.1-cp39-cp39-manylinux2014_x86_64.whl (4.1 MB)
Requirement already satisfied: six>=1.5.2 in /home/vscode/.local/lib/python3.9/site-packages (from grpcio==1.36.1->iosxr-grpc==1.3) (1.15.0)
Collecting protobuf==3.15.6
  Using cached protobuf-3.15.6-cp39-cp39-manylinux1_x86_64.whl (1.0 MB)
Installing collected packages: protobuf, grpcio, iosxr-grpc
  Running setup.py develop for iosxr-grpc
Successfully installed grpcio-1.36.1 iosxr-grpc protobuf-3.15.6

setup.py also needs to be updated for pypi

from setuptools import setup


setup(name='iosxr_grpc',
      version='1.3',
      description='gRPC library for IOS-XR > 6.1.1',
      url='https://github.com/cisco-grpc-connection-libs/ios-xr-grpc-python',
      author='Karthik Kumaravel',
      authoer_email='srirudrankumaravel@gmail.com',
      licencse='Apache 2.0',
      packages=['iosxr_grpc'],
      install_requires=[
          'grpcio==1.36.1',
          'protobuf==3.15.6',
      ],
      zip_safe=False)