Lints for abi3 packages

We have an example for abi3 at https://github.com/conda-forge/python-abi3-feedstock/blob/main/recipe/example-recipe.yaml, but some packages are carrying around workarounds for bugs in conda-build and rattler-build around. We should provide some lints to remove those workarounds and also some lints for best practices. - [x] remove python_min redefinitions that match the global pinning default - https://github.com/conda-forge/conda-smithy/pull/2581 - [x] python version independent recipes (abi3 for eg) should test for python latest too - https://github.com/conda-forge/conda-smithy/pull/2580 - [x] Remove rattler-build workaround for SP_DIR not being defined. - See for example https://github.com/conda-forge/fsspec-rs-feedstock/blob/main/recipe/recipe.yaml#L59-L63 - https://github.com/conda-forge/conda-smithy/pull/2619 - [x] Remove rattler-build workaround for cross-python run_exports for abi3 packages - See for example https://github.com/conda-forge/fsspec-rs-feedstock/blob/main/recipe/recipe.yaml#L46-L48 - github.com/conda-forge/conda-smithy/pull/2630 - [x] Check that abi3 packages use abi3audit. - github.com/conda-forge/conda-smithy/pull/2640