coremltools is python-dependent in requires_dist

Makes the `coremltools` version explicitly dependent on the Python version in `install_requires`

Author: Malcolm Greaves

src/python/setup.py

@@ -181,9 +181,9 @@ def do_not_install(require):
 
     if sys.version_info[0] == 3 and sys.version_info[1] == 8:
         # Only 4.0 betas support Python 3.8
-        install_requires.append("coremltools==4.0b3")
+        install_requires.append("coremltools==4.0b3; python_version >= 3.8.0',")
     else:
-        install_requires.append("coremltools==3.3")
+        install_requires.append("coremltools==3.3; python_version < 3.8.0")
 
     if sys.platform == "darwin":
         install_requires.append("tensorflow >= 2.0.0")