Switch to v2 of docker build workflow

Author: bennettgoble

.github/workflows/ci.yaml

@@ -17,7 +17,7 @@ jobs:
         run: docker build --target test .
   docker:
     needs: test
-    uses: secondlife/docker-build-workflow/.github/workflows/build.yml@signal/semver-latest
+    uses: secondlife/docker-build-workflow/.github/workflows/build.yml@v2
     with:
       image: platform/nginx-proxy 
       platforms: linux/amd64,linux/arm64