Update format_version set when creating new packages (#1303)

Author: mrodm

internal/packages/archetype/package_manifest.go

@@ -4,7 +4,7 @@
 
 package archetype
 
-const packageManifestTemplate = `format_version: 2.5.1
+const packageManifestTemplate = `format_version: 2.8.0
 name: {{.Manifest.Name}}
 title: "{{.Manifest.Title}}"
 version: {{.Manifest.Version}}