Add tests by other authentication and CI workflow for running tests

[t-ham752]

Thank you for creating such a wonderful library.
I also wanted to contribute something, so I worked on the following issues:

• Add test for other authentication methods: PrivateKey and Agent #40
• Enable Continuous Integration using Github Actions #44

After working on /issues/40, I found issue /issues/44 and understood that you wanted to remove the bash script.

However, it seemed quite challenging to include the removal of the bash script, so I focused on the following:

• Adding test cases other than password authentication
• Adding CI with GitHub Actions

I would be happy if I could contribute. Please review it when you have time.

[bramvdbogaerde]

Merged! Thanks for your contribution! I noticed that the authentication methods other than password do not seem to work on Github Actions so I added an additional check to the script to disable them when the tests are executed on Github Actions.