Update .github/workflows/autobuild.yml

Co-authored-by: ann0see <20726856+ann0see@users.noreply.github.com>

Author: pljones

.github/workflows/autobuild.yml

@@ -226,7 +226,7 @@ jobs:
 
           - config_name:            MacOS (artifacts)
             target_os:              macos
-            building_on_os:         macos-15
+            building_on_os:         macos-26
             base_command:           QT_VERSION=6.9.1 SIGN_IF_POSSIBLE=1 TARGET_ARCHS="x86_64 arm64" ./.github/autobuild/mac.sh
             # Disable CodeQL on mac as it interferes with signing the binaries (signing hangs, see #2563 and #2564)
             run_codeql:             false