update(.golangci.yml): add spdx id line to the linter

Co-authored-by: Aldo Lacuku <[email protected]>
Signed-off-by: Leonardo Grasso <[email protected]>

.golangci.yml

@@ -11,6 +11,7 @@ linters-settings:
       const:
         AUTHORS: The Falco Authors
     template: |-
+      SPDX-License-Identifier: Apache-2.0
       Copyright {{ YEAR }} {{ AUTHORS }}
 
       Licensed under the Apache License, Version 2.0 (the "License");