Clarify unit test workflow

[Maghnie]

Current situation:

Currently, there are seemingly three ways of setting up the environment for the unit tests but apparently only one works (for me).

1. The tests readme says to create a '.env.filip' file
2. The included .env template says to create a '.env' file
3. There's a third env file called 'test_config.env'. Not sure if this serves a different purpose.

Suggestion:

1. Update the readme to refer to a '.env' file
2. Remove 'test_config.env' and any corresponding references?

[Maghnie]

@djs0109 Thoughts?

[djs0109]

Thank you for reporting this importing issue. Yes, we must revise the readme in tests.

1. It is outdated. the .env.filip should only be needed for filip examples and tutorials
2. It is correct
3. test_config.env is needed for a unittest