codec: updated GenVersion to 13: removed DecodeString() - use DecodeStringAsBytes

codec/gen-helper.generated.go

@@ -13,7 +13,7 @@ import (
 )
 
 // GenVersion is the current version of codecgen.
-const GenVersion = 12
+const GenVersion = 13
 
 // This file is used to generate helper code for codecgen.
 // The values here i.e. genHelper(En|De)coder are not to be used directly by