Fix GH Workflow. Use Xcode 15.3

Author: Carlos Cabanero

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
     - uses: actions/checkout@v2
 
     - name: xcode-select
-      run: sudo xcode-select -s /Applications/Xcode_12.3.app
+      run: sudo xcode-select -s /Applications/Xcode_15.3.app
 
     - name: install autoreconf
       run: brew install automake
@@ -54,4 +54,4 @@ jobs:
         upload_url: ${{ steps.create_release.outputs.upload_url }} 
         asset_path: ./OpenSSH-static.xcframework.zip
         asset_name: OpenSSH-static.xcframework.zip
-        asset_content_type: application/zip
+        asset_content_type: application/zip