benchmarks/ddosify: Update to 0.15.0

ChangeLog: https://github.com/ddosify/ddosify/releases/tag/v0.15.0

Introducing engine modes:

engine_mode is optional in the config file.

 * distinct-user mode simulates a new user for every iteration.
 * repeated-user mode can use pre-used user in subsequent iterations.
 * ddosify mode is the default mode of the engine. In this mode, the engine
   runs in its max capacity, and does not show user simulation behavior.

Add breaking changes to UPDATING

PR:		270078
Reported by:	0xdutra@gmail.com (maintainer)

UPDATING

@@ -5,6 +5,14 @@ they are unavoidable.
 You should get into the habit of checking this file for changes each time
 you update your ports collection, before attempting any port upgrades.
+20230310:
+  AFFECTS: user of benchmarks/ddosify
+  AUTHOR: fernape@FreeBSD.org
+
+  keep-alive is removed from config file. In default mode, the engine will use
+  keep-alive for all requests. If you want to disable keep-alive for a step, you
+  can add Connection: close header to the step.
+
 20230306:
   AFFECTS: users of www/qt5-webengine
   AUTHOR: kai@FreeBSD.org

benchmarks/ddosify/Makefile

 PORTNAME=	ddosify
 DISTVERSIONPREFIX=	v
-DISTVERSION=	0.14.1
-PORTREVISION=	1
+DISTVERSION=	0.15.0
 CATEGORIES=	benchmarks
 
 MAINTAINER=	0xdutra@gmail.com

benchmarks/ddosify/distinfo

-TIMESTAMP = 1677211717
-SHA256 (ddosify-ddosify-v0.14.1_GH0.tar.gz) = f6cf425377677122920b69f04bdb217ba894bfea2211aced6860b7087c744b88
-SIZE (ddosify-ddosify-v0.14.1_GH0.tar.gz) = 1193951
+TIMESTAMP = 1678073310
+SHA256 (ddosify-ddosify-v0.15.0_GH0.tar.gz) = b8aed6594b765abf62c0bc5dcbfa49cd6d629b3ff7c0a7bcc14253a45c67e0c6
+SIZE (ddosify-ddosify-v0.15.0_GH0.tar.gz) = 1197164
 SHA256 (antchfx-xmlquery-v1.3.13_GH0.tar.gz) = e882143ac161874fc3d9a91f1e19ab78271b5aa37a7d8541e728b566c405e36c
 SIZE (antchfx-xmlquery-v1.3.13_GH0.tar.gz) = 21490
 SHA256 (antchfx-xpath-v1.2.1_GH0.tar.gz) = cd9962512d4b3611b500621c1aeaf12780648845f7c976050c2bcba5c5d222c4