gfortran v15.1.0, v14.3.0 & v13.4.0; drop v12

[h-vetinari]

Waiting for conda-forge/gfortran_impl_osx-64-feedstock#92

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

I do have some suggestions for making it better though...

For recipe/meta.yaml:

• ℹ️ The recipe is not parsable by parser conda-souschef (grayskull). This parser is not currently used by conda-forge, but may be in the future. We are collecting information to see which recipes are compatible with grayskull.

_{This message was generated by GitHub Actions workflow run https://github.com/conda-forge/conda-forge-webservices/actions/runs/15791268108. Examine the logs at this URL for more detail.}

[h-vetinari]

This is ready modulo one small question (see below). PTAL @conda-forge/gfortran_osx-64

[h-vetinari]

Ping @conda-forge/gfortran_osx-64

[h-vetinari]

Ping @isuruf

[isuruf]

Thanks