add unit tests

[flepied]

• add some unit tests in tests/test_streaming_indicators.py
• add a GitHub workflow to run the unit tests
• fix a bug in SMMA detected by the unit tests

[mr-easy]

thanks for this, this was one of the long pending task. will merge this after checking.
Can you create some more test cases using talib? I consider talib to be de-facto library for technical indicators, and our calculations should match talib's. I usually do this on my local whenever I create a new indicator.
We can keep some sample data, and for each indicator existing (and whenever newly added), create a mapping with talib function.

[flepied]

I would prefer to add TA-lib verification in another PR, as this will require extra steps to install TA-lib. Could you approve the workflow to see if the GitHub action is working? I cannot test it locally...