Correctly enforce minimum macOS version.

Makefile

@@ -65,7 +65,7 @@ CURL_FLAGS=--disable --fail --location --create-dirs --progress-bar
 
 # macOS targets
 TARGETS-macOS=macosx.x86_64 macosx.arm64
-VERSION_MIN-macOS=10.15
+VERSION_MIN-macOS=11.0
 CFLAGS-macOS=-mmacosx-version-min=$(VERSION_MIN-macOS)
 
 # iOS targets
@@ -846,6 +846,7 @@ $$(PYTHON_SRCDIR-$(sdk))/Makefile: \
 			LIBLZMA_LIBS="-L$$(XZ_MERGE-$(sdk))/lib -llzma" \
 			BZIP2_CFLAGS="-I$$(BZIP2_MERGE-$(sdk))/include" \
 			BZIP2_LIBS="-L$$(BZIP2_MERGE-$(sdk))/lib -lbz2" \
+			MACOSX_DEPLOYMENT_TARGET="$$(VERSION_MIN-$(os))" \
 			--prefix="$$(PYTHON_INSTALL-$(sdk))" \
 			--enable-ipv6 \
 			--enable-universalsdk \

README.rst

@@ -4,14 +4,15 @@ Python Apple Support
 This is a meta-package for building a version of Python that can be embedded
 into a macOS, iOS, tvOS or watchOS project.
 
-**This branch builds a packaged version of Python 3.12.0**.
+**This branch builds a packaged version of Python 3.13.0**.
 Other Python versions are available by cloning other branches of the main
 repository:
 
 * `Python 3.8 <https://github.com/beeware/Python-Apple-support/tree/3.8>`__
 * `Python 3.9 <https://github.com/beeware/Python-Apple-support/tree/3.9>`__
 * `Python 3.10 <https://github.com/beeware/Python-Apple-support/tree/3.10>`__
 * `Python 3.11 <https://github.com/beeware/Python-Apple-support/tree/3.11>`__
+* `Python 3.12 <https://github.com/beeware/Python-Apple-support/tree/3.12>`__
 
 It works by downloading, patching, and building a fat binary of Python and selected
 pre-requisites, and packaging them as static libraries that can be incorporated into an
@@ -41,10 +42,10 @@ The binaries support x86_64 and arm64 for macOS; arm64 for iOS and appleTV
 devices; and arm64_32 for watchOS. It also supports device simulators on both
 x86_64 and M1 hardware. This should enable the code to run on:
 
-* macOS 10.15 (Catalina) or later, on:
+* macOS 11 (Big Sur) or later, on:
     * MacBook (including MacBooks using Apple Silicon)
     * iMac (including iMacs using Apple Silicon)
-    * Mac Mini (including M1 Apple Silicon Mac minis)
+    * Mac Mini (including Apple Silicon Mac minis)
     * Mac Studio (all models)
     * Mac Pro (all models)
 * iOS 12.0 or later, on: