CI: use conda to install bmad in GitHub Actions

[ken-lauer]

• Tests on Python 3.9-3.12
• Installs bmad with conda

[ken-lauer]

2 failures, 111 passed - failures unexpected to me:

>           raise RuntimeError(f'Command: {cmd} causes error: {err}')
E           RuntimeError: Command: python beam 1 causes error: ERROR detected: [ERROR | 2024-JUN-20 20:59:34] tao_python_cmd:
E               "python beam 1": Out of range branch index
E           INVALID

pytao/tao_ctypes/core.py:157: RuntimeError
_______________________________ test_beam_init_1 _______________________________

    def test_beam_init_1():
    
        tao = Tao(os.path.expandvars('-init $ACC_ROOT_DIR/regression_tests/python_test/csr_beam_tracking/tao.init -noplot'))
>       ret = interface_commands.beam_init(tao, ix_uni='1')

pytao/tests/test_interface_commands.py:22: 

Is this because maybe the bmadmaster version vs the generated test suite differ? (@ChristopherMayes?)

[ChristopherMayes]

master should be close to the release for this purpose.

[ken-lauer]

Closing/re-opening: retrying test suite to see if the unexpected errors magically go away 🤞

[ken-lauer]

There were python command updates for tao: bmad-sim/bmad-ecosystem@7da7f46

[ChristopherMayes]

I reported in bmad-sim/bmad-ecosystem#1016

[ken-lauer]

This is reportedly fixed upstream; can you reapprove the GHA workflow @ChristopherMayes ?

[hhslepicka]

Approved @ken-lauer

[ken-lauer]

Thanks @hhslepicka !
Tests are now passing 🥳