Update MACOSX_DEPLOYMENT_TARGET parsing

Now allows versions with other than "major.minor" i.e. "major" or "major.minor.patch"

Author: mayeut

cibuildwheel/macos.py

@@ -267,7 +267,16 @@ def setup_python(
     # retrieve the one supplied by the user, otherwise 10.9 is supported with every installer.
     # An exception can be made for wheel built explicitly for arm64, this will be fixed later on.
     # PyPy defaults to 10.7, causing inconsistencies if it's left unset.
-    deployment_target = tuple(map(int, env.get("MACOSX_DEPLOYMENT_TARGET", "10.9").split(".")))
+    # it's valid to set e.g. MACOSX_DEPLOYMENT_TARGET=10.12.1 or MACOSX_DEPLOYMENT_TARGET=11
+    # always normalize as tuple(major, minor)
+    deployment_target = tuple(map(int, env.get("MACOSX_DEPLOYMENT_TARGET", "10.9").split(".")[:2]))
+    if deployment_target[0] >= 11:
+        # starting with macOS 11, the minor version in fact represents patch version
+        deployment_target = (deployment_target[0], 0)
+    if len(deployment_target) < 2:
+        # even though it didn't make much sense before macOS 11, it was valid to set
+        # MACOSX_DEPLOYMENT_TARGET=10 which is 10.0
+        deployment_target = (deployment_target[0], 0)
 
     config_is_arm64 = python_configuration.identifier.endswith("arm64")
     config_is_universal2 = python_configuration.identifier.endswith("universal2")