chore: go mod tidy after removing direct digitorus/timestamp import

Signed-off-by: Jose I. Paris <jiparis@chainloop.dev>

Author: jiparis

go.mod

@@ -346,7 +346,7 @@ require (
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/desertbit/timer v0.0.0-20180107155436-c41aec40b27f // indirect
 	github.com/digitorus/pkcs7 v0.0.0-20230818184609-3a137a874352 // indirect
-	github.com/digitorus/timestamp v0.0.0-20231217203849-220c5c2851b7
+	github.com/digitorus/timestamp v0.0.0-20231217203849-220c5c2851b7 // indirect
 	github.com/docker/cli v29.2.0+incompatible // indirect
 	github.com/docker/docker v28.5.2+incompatible // indirect
 	github.com/docker/docker-credential-helpers v0.9.4 // indirect