Remove ECR login

Author: marcoacierno

.github/workflows/build-base-pretix.yml

@@ -22,8 +22,6 @@ jobs:
         with:
           repository: pretix/pretix
           ref: ${{ inputs.version }}
-      - name: Login to Amazon ECR
-        uses: aws-actions/amazon-ecr-login@v2
       - name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v3