Update development status from alpha to beta

[msimberg]

I would no longer consider icon4py alpha software. This updates the status to beta for all packages. See https://pypi.org/classifiers/ for available classifiers.

Open question: should we leave some packages (e.g. standalone driver) as alpha? Conversely, should anything be production/stable (e.g. dycore/diffusion)?

[github-actions]

Mandatory Tests

Please make sure you run these tests via comment before you merge!

• cscs-ci run default
• cscs-ci run distributed

Optional Tests

To run benchmarks you can use:

• cscs-ci run benchmark-bencher

To run tests and benchmarks with the DaCe backend you can use:

• cscs-ci run dace

To run test levels ignored by the default test suite (mostly simple datatest for static fields computations) you can use:

• cscs-ci run extra

For more detailed information please look at CI in the EXCLAIM universe.

[nfarabullini]

I would say that dycore and diffusion can be classified as production stable. I don't have particular feelings about standalone driver, as I feel like it's in between alpha and beta