Increase macOS deployment target to 11.0 for Skia m143

Skia m143 uses std::optional::value() which requires macOS 10.13+.
Setting to 11.0 to match Skia's own build configuration and ensure
compatibility when building from source.

Author: anthrotype

build_skia.py

@@ -205,7 +205,7 @@ def build_skia(
 
     # https://github.com/fonttools/skia-pathops/issues/41
     if sys.platform == "darwin":
-        env["MACOSX_DEPLOYMENT_TARGET"] = "10.9"
+        env["MACOSX_DEPLOYMENT_TARGET"] = "11.0"
 
     if args.sync_deps:
         subprocess.check_call(