fix: Use request time to compute the retry after (open-feature#846)

Author: thomaspoignant

libs/shared/ofrep-core/src/lib/api/errors.ts

@@ -91,7 +91,7 @@ export class OFREPApiTooManyRequestsError extends OFREPApiError {
         return null;
       }
 
-      return new Date(Date.now() + this.retryAfterSeconds * 1000);
+      return new Date(this.requestTime.getTime() + this.retryAfterSeconds * 1000);
     }
 
     const date = new Date(this.retryAfterHeader);