Update build-push-action to v6 and switch to branch main

.github/workflows/build-latest.yaml

@@ -3,7 +3,7 @@ name: build-latest
 on:
   push:
     branches:
-      - 'master'
+      - 'main'
     paths:
     - '**'
     - '.github/workflows/build-latest.yaml'
@@ -43,12 +43,12 @@ jobs:
       -
         name: Build and push
         id: docker_build
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: true
           tags: hub.ncsa.illinois.edu/des-public/desdm-public:latest
-          # From https://github.com/docker/build-push-action/blob/master/docs/advanced/cache.md#github-cache
+          # From https://github.com/docker/build-push-action/blob/main/docs/advanced/cache.md#github-cache
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache-new
       -