fix(release): add provenance=false flag for docker builds

Add the --provenance=false flag to all Docker builds via the flags field
to ensure compatibility with registries that do not support buildx
provenance attestations, particularly the Heroku Container Registry.

Signed-off-by: Sebastian Webber <sebastian@swebber.me>

Author: sebastianwebber

.goreleaser.yml

@@ -144,6 +144,9 @@ dockers_v2:
     platforms:
       - linux/amd64
       - linux/arm64
+    flags:
+      - "--provenance=false"
+    sbom: false
 
   - id: api
     ids:
@@ -170,4 +173,6 @@ dockers_v2:
     platforms:
       - linux/amd64
       - linux/arm64
-
+    flags:
+      - "--provenance=false"
+    sbom: false