Delete some ancient checks for MacOS builds

As we no longer build for Python-2.7 or 3.5

wheel/build_wheel.sh

@@ -97,16 +97,7 @@ fi
 whl_tmp_dir="${MAC_PACKAGE_WORK_DIR}/dist"
 mkdir -p "$whl_tmp_dir"
 
-# Python 3.5 build against macOS 10.6, others build against 10.9
-# NB: Sometimes Anaconda revs the version, in which case you'll have to
-# update this!
-# An example of this happened on Aug 13, 2019, when osx-64/python-2.7.16-h97142e2_2.tar.bz2
-# was uploaded to https://anaconda.org/anaconda/python/files
-if [[ "$desired_python" == 3.5 ]]; then
-    mac_version='macosx_10_6_x86_64'
-elif [[ "$desired_python" == 2.7 ]]; then
-    mac_version='macosx_10_7_x86_64'
-elif [[ -n "$CROSS_COMPILE_ARM64" ]]; then
+if [[ -n "$CROSS_COMPILE_ARM64" || $(uname -m) == "arm64" ]]; then
     mac_version='macosx_11_0_arm64'
 else
     mac_version='macosx_10_9_x86_64'