correctly use subdirectory for discord_build.yml

Author: hry-gh

.github/workflows/discord_build.yml

@@ -24,9 +24,6 @@ jobs:
       id-token: write
 
     steps:
-      - name: Checkout repository
-        uses: actions/checkout@v4
-
       # Set up BuildKit Docker container builder to be able to build
       # multi-platform images and export cache
       # https://github.com/docker/setup-buildx-action
@@ -56,7 +53,7 @@ jobs:
         id: build-and-push
         uses: docker/build-push-action@0565240e2d4ab88bba5387d719585280857ece09 # v5.0.0
         with:
-          context: .
+          context: "{{defaultContext}}:tools/od_ref_bot"
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}