Fix dockerfile typos

Author: Kate Osborn

.github/workflows/ci.yml

@@ -300,7 +300,7 @@ jobs:
       - name: Build Docker Image
         uses: docker/build-push-action@2eb1c1961a95fc15694676618e422e8ba1d63825 # v4.1.1
         with:
-          file: ${{ matrix.container == 'nginx' && 'build/dockerfile.nginx' || 'build.dockerfile' }}
+          file: ${{ matrix.container == 'nginx' && 'build/Dockerfile.nginx' || 'build/Dockerfile' }}
           context: "."
           target: ${{ matrix.container == 'nkg' && 'goreleaser' || '' }}
           tags: ${{ steps.meta.outputs.tags }}