Set min MacOSX req to 10.12

Author: dstansby

.github/workflows/cibuildwheel.yml

@@ -30,6 +30,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     env:
       CIBW_ARCHS_MACOS: "x86_64 universal2 arm64"
+      MACOSX_DEPLOYMENT_TARGET: "10.12"
     strategy:
       matrix:
         os: [ubuntu-18.04, windows-latest, macos-10.15]

doc/devel/dependencies.rst

@@ -47,6 +47,7 @@ and the capabilities they provide.
 * pycairo_ (>= 1.11.0) or cairocffi_ (>= 0.8): for the GTK and/or cairo-based
   backends.
 * Tornado_ (>=5): for the WebAgg backend.
+* macOS (>=10.12): for the macosx backend.
 
 .. _Tk: https://docs.python.org/3/library/tk.html
 .. _PyQt5: https://pypi.org/project/PyQt5/

doc/users/next_whats_new/min_macos_version.rst

@@ -0,0 +1,3 @@
+New minimum macOS version
+-------------------------
+The macosx backend now requires macOS >= 10.12.