update to newer xcode

Author: mattip

.github/workflows/posix.yml

@@ -96,7 +96,7 @@ jobs:
     - uses: maxim-lobanov/setup-xcode@v1.6.0
       if: ${{ matrix.os == 'macos-latest' }}
       with:
-        xcode-version: '14.3'
+        xcode-version: '15.4'
 
     - name: Print some Environment variable
       run: |

tools/local_build.sh

@@ -65,8 +65,8 @@ function build_openblas {
     # Build OpenBLAS
     set -xeo pipefail
     if [ "$PLAT" == "arm64" ]; then
-      sudo xcode-select -switch /Applications/Xcode_12.5.1.app
-      export SDKROOT=/Applications/Xcode_12.5.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk
+      sudo xcode-select -switch /Applications/Xcode_15.4.0.app
+      export SDKROOT=/Applications/Xcode_15.4.0-app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk
       clang --version
     fi
     source tools/build_steps.sh