Update meta.yaml

[TomAugspurger]

Unskip osx. Now that we're not in staged-recipes our conda-build-config.yaml should be used.

Checklist

• [x] Used a personal fork of the feedstock to propose changes
• [x] Bumped the build number (if the version is unchanged)
• [ ] Reset the build number to 0 (if the version changed)
• [ ] Re-rendered with the latest conda-smithy (Use the phrase code>@<space/conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• [x] Ensured the license file is being packaged.

[TomAugspurger]

@conda-forge-admin, please rerender

[conda-forge-linter]

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) and found it was in an excellent condition.

[TomAugspurger]

MACOSX_DEPLOYMENT_TARGET was correctly set to 10.13, but we still see some errors.

/Users/runner/miniforge3/conda-bld/coremltools_1602878171309/work/coremlpython/CoreMLPythonUtils.h:39:53: error: unknown type name 'MLSequence'
            py::object convertSequenceValueToPython(MLSequence *seq) API_AVAILABLE(macos(10.14));
                                                    ^
/Users/runner/miniforge3/conda-bld/coremltools_1602878171309/work/coremlpython/CoreMLPython.mm:61:13: error: unknown type name 'MLModelConfiguration'
            MLModelConfiguration *configuration = [MLModelConfiguration new];
            ^
/Users/runner/miniforge3/conda-bld/coremltools_1602878171309/work/coremlpython/CoreMLPython.mm:61:52: error: use of undeclared identifier 'MLModelConfiguration'
            MLModelConfiguration *configuration = [MLModelConfiguration new];
                                                   ^
/Users/runner/miniforge3/conda-bld/coremltools_1602878171309/work/coremlpython/CoreMLPython.mm:63:46: error: use of undeclared identifier 'MLComputeUnitsCPUOnly'
                configuration.computeUnits = MLComputeUnitsCPUOnly;
                                             ^

Oh https://github.com/apple/coremltools/issues/456#issuecomment-539620896 indicates that 10.14 is required. I'm not sure where I got 10.13 from.

[TomAugspurger]

@conda-forge-admin, please rerender