add buildx plugin

Author: drifter089

.github/workflows/devcontainer.yml

@@ -31,9 +31,12 @@ jobs:
     - name: Setup docker (missing on MacOS)
       if: runner.os == 'macos'
       run: |
-        brew install docker
+        brew install docker docker-buildx
         brew install colima
         colima start
+        while ! docker info >/dev/null 2>&1; do sleep 1; done
+        mkdir -p ~/.docker/cli-plugins
+        ln -sfn $(which docker-buildx) ~/.docker/cli-plugins/docker-buildx
     
     - name: Login to GitHub Container Registry
       uses: docker/login-action@v2
@@ -43,8 +46,6 @@ jobs:
         password: ${{ secrets.REGISTRY_TOKEN }}
     - 
       name: Build Dev Container Image
-      env: 
-        DOCKER_BUILDKIT: ${{ runner.os == 'macOS' && '0' || '' }}
       uses: devcontainers/ci@v0.2
       with:
         subFolder: .github
@@ -53,8 +54,6 @@ jobs:
         push: never  
 
     - name: Test Container Image
-      env: 
-        DOCKER_BUILDKIT: ${{ runner.os == 'macOS' && '0' || '' }}  
       run: |
         docker run --rm ghcr.io/${{ github.repository }} /bin/bash -c  "git clone -b devContainers https://github.com/drifter089/pypsa-earth.git && cd pypsa-earth && bash .github/.devcontainer/test.sh"