ci: test that setup-fpm passes all the fpm tests

[gnikit]

Fixes #9

I thought it would be quite appropriate (and somewhat funny) to check that fpm-setup works by running the fpm test suite.

[everythingfunctional]

I like it.

[gnikit]

@everythingfunctional we might want to enable the fortran-setup only for macos where things are failing without it, because Linux and Windows are super slow to install also I get warning for the Windows setup for the compiler+version not being recognised (which we should be getting). I suspect that this is a fortran-setup bug though.

[everythingfunctional]

@gnikit , depends how confident you are that things will continue to work on Linux and Windows without it.

[gnikit]

@gnikit , depends how confident you are that things will continue to work on Linux and Windows without it.

Good point, confidence level should be low. So I'll merge and we'll take the CI runtime hit for now, until I setup caching for the compilers in setup-fortran.