fix: force nightly Caddy rebuild through the correct cache key

Ensure the nightly image does not reuse a stale Caddy builder layer, which
was allowing the published image to keep reporting Caddy 2.11.2 even after
the Dockerfile pin moved to 2.11.3.

This change corrects the Buildx cache exclusion input so the nightly pipeline
actually rebuilds the Caddy stage before publishing and scanning the image.
That prevents the supply-chain checks and GitHub security reporting from being
fed an outdated binary.

Author: Wikid82

.github/workflows/nightly-build.yml

@@ -226,7 +226,7 @@ jobs:
             ALPINE_IMAGE=${{ steps.alpine.outputs.image }}
           cache-from: type=gha
           cache-to: type=gha,mode=max
-          no-cache-filter: caddy-builder
+          no-cache-filters: caddy-builder
           provenance: true
           sbom: true