asyncio.coroutine has been deprecated since Python 3.8 over async def syntax

[tirkarthi]

Following tests emit deprecation warning regarding this as below :

tests/test_objects.py
80:        @asyncio.coroutine
103:        @asyncio.coroutine

tests/test_functions.py
176:        @asyncio.coroutine
199:        @asyncio.coroutine

tests/test_functions.py::CoroutineFunction::test_coroutine__decorator
  /root/checked_repos/callee/tests/test_functions.py:177: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def coro_func(loop):

tests/test_functions.py::CoroutineFunction::test_coroutine_function__decorator
  /root/checked_repos/callee/tests/test_functions.py:200: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def coro_func(loop):

tests/test_objects.py::Coroutine::test_coroutine__decorator
  /root/checked_repos/callee/tests/test_objects.py:81: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def coro_func(loop):

tests/test_objects.py::Coroutine::test_coroutine_function__decorator
  /root/checked_repos/callee/tests/test_objects.py:104: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
    def coro_func(loop):