Implement basic integration tests and continuous integration

[marcosfelt]

Set up Github actions and ~use pytest mock to mock _resilient_request~ and add ~units~ tests for the following services.

• [x] Github actions #8
• [x] OPSIN #5
• [x] OPSIN batchmode #11
• [ ] Pubchem
• [ ] CompTox
• [ ] CTS
• [ ] Chemeo
• [ ] CAS
• [ ] CIR
• [ ] NIST
• [ ] CHEBI

I need to note down for each service which examples are failing and add a json field with services that are expected to fail. Then, I could check if the behavior is doing what we want. Going to do the unit tests in a separate issue.

[simonmb]

To mock the request maybe the best would be to run the moleculeresolver on a set of molecules and save the status code and the content of the request let's say for example to a json file used in the mock? Do you need a list of identifiers/modes to do this?

[marcosfelt]

That's a good idea - maybe we could have a script that does this. Would you be able to write that?

[simonmb]

Yes I'll send you a json with identifiers and modes via email.