fix misattributed property parent in deprecation warning: request.elapsedTime -> reply.elapsedTime (fastify#5299)

Author: mscottnelson

lib/warnings.js

@@ -79,7 +79,7 @@ const FSTDEP019 = createDeprecation({
 
 const FSTDEP020 = createDeprecation({
   code: 'FSTDEP020',
-  message: 'You are using the deprecated "reply.getResponseTime()"" method. Use the "request.elapsedTime" property instead. Method "reply.getResponseTime()" will be removed in `fastify@5`.'
+  message: 'You are using the deprecated "reply.getResponseTime()" method. Use the "reply.elapsedTime" property instead. Method "reply.getResponseTime()" will be removed in `fastify@5`.'
 })
 
 const FSTWRN001 = createWarning({