tests/acceptance: Bump avocado requirements to 83.0

To use Avocado's testlogs plug-in on CI it is required to use
its 83.0 or greater version.

Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Message-Id: <20201211183827.915232-2-wainersm@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/requirements.txt

 # Add Python module requirements, one per line, to be installed
 # in the tests/venv Python virtual environment. For more info,
 # refer to: https://pip.pypa.io/en/stable/user_guide/#id1
-avocado-framework==81.0
+avocado-framework==83.0
 pycdlib==1.11.0