Kenneth Hsu 94392bf2b7 Remove step to install mono, which is already included. ...

According to the documentation, mono is already included in the
ubuntu-latest virtual environment:

https://github.com/actions/virtual-environments/blob/ubuntu18/20210131.1/images/linux/Ubuntu1804-README.md

2021-02-08 15:47:52 -08:00

..

tests.yml

Remove step to install mono, which is already included.

2021-02-08 15:47:52 -08:00