Update Darwin build job to run on macOS latest and configure Docker machine

.github/workflows/pr-build.yml

@@ -74,7 +74,7 @@ jobs:
           path: agent-${{matrix.architecture}}.tar
           
   build-darwin:
-    runs-on: macos-26
+    runs-on: macos-latest
     permissions:
       contents: write
     strategy:
@@ -86,6 +86,8 @@ jobs:
           mkdir -p ~/.docker/machine/cache
           curl -Lo ~/.docker/machine/cache/boot2docker.iso https://github.com/boot2docker/boot2docker/releases/download/v19.03.12/boot2docker.iso
           brew install docker docker-machine
+          docker-machine create --driver virtualbox default
+          docker-machine env default
       - name: Login to DockerHub
         uses: docker/login-action@v2
         with: