feature: MIR_CI_SERVER environment variable to express external servers

[mattkae]

What's new?

• We can now specify a MIR_CI_SERVER and the specified server will be included in our runs

How to test

MIR_CI_SERVER=snap:<SOME_OTHER_MIR_BASED_SHELL>:ALL pytest -k <SOME_OTHER_MIR_BASED_SHELL>

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 91.66667% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 68.85%. Comparing base (1903e8f) to head (b162e2e). Report is 5 commits behind head on main.

Files	Patch %	Lines
mir-ci/mir_ci/fixtures/servers.py	91.89%	3 Missing :warning:
mir-ci/mir_ci/conftest.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #113 +/- ## ========================================== + Coverage 67.59% 68.85% +1.26% ========================================== Files 16 16 Lines 827 867 +40 Branches 115 125 +10 ========================================== + Hits 559 597 +38 - Misses 244 246 +2 Partials 24 24 ```

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[mattkae]

And probably -W error:: it, too.

What do you mean by this part?

[Saviq]

What do you mean by this part?

We should make this warning a fail by default, through a config in pytest.ini:

https://docs.pytest.org/en/7.1.x/how-to/capture-warnings.html#controlling-warnings

Otherwise you might miss that you provided an invalid one.