www/xcaddy: add missing RUN_DEPENDS on lang/go.

xcaddy uses go to build custom releases of caddy, so it actually needs
it at runtime.

PR:		279358
Reported by:	Robert William Vesterman <bob@vesterman.com>

www/xcaddy/Makefile

 PORTNAME=	xcaddy
 DISTVERSIONPREFIX=	v
 DISTVERSION=	0.4.1
+PORTREVISION=	1
 CATEGORIES=	www
 DIST_SUBDIR=	xcaddy
 
@@ -11,6 +12,9 @@ WWW=		https://github.com/caddyserver/xcaddy
 LICENSE=	APACHE20
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
+# xcaddy actually needs to run the go command to perform builds
+RUN_DEPENDS=	go:lang/go
+
 USES=		go:modules
 
 USE_GITHUB=	yes