Pin pytest-cov to 2.9.0
Pin pytest-cov to 2.9.0

Signed-off-by: Vinzenz Feenstra <600e8a10eeff4f08c65e2cf493cd851025e86fd2@redhat.com>

leapp-to/prototype,leapp-to/prototype,leapp-to/prototype,leapp-to/prototype