remove missing artifact

Signed-off-by: Alexander Dahmen <alexander.dahmen@inovex.de>

Author: Fyusel

.goreleaser.yaml

@@ -28,7 +28,6 @@ signs:
     env:
       - COSIGN_EXPERIMENTAL=1
     signature: '${artifact}.sig'
-    certificate: '${artifact}.pem'
     args:
       - sign-blob
       - '-y'