[Backport 7.x] Added new observability events (#1370)

Co-authored-by: Tomas Della Vedova <delvedor@users.noreply.github.com>

index.d.ts

@@ -2601,8 +2601,10 @@ declare class Client {
 }
 
 declare const events: {
-  RESPONSE: string;
+  SERIALIZATION: string;
   REQUEST: string;
+  DESERIALIZATION: string;
+  RESPONSE: string;
   SNIFF: string;
   RESURRECT: string;
 };