graphics/vulkan-headers: pacify stage-qa after 93b836b

Error: '/usr/bin/python3' is an invalid shebang you need USES=shebangfix for 'share/vulkan/registry/genvk.py'

genvk.py is used to generate include/vulkan/*.h but distfile already
contains pregerenated version, so the shebang is unused. Regenerating
headers isn't supported by CMake build, and requires docgenerator.py
from Vulkan-Docs repo.

PR:		268489
Reported by:	amdmi3
Regressed by:	KhronosGroup/Vulkan-Headers@75a6b83f213d

Author: jbeich

graphics/vulkan-headers/Makefile

@@ -1,6 +1,7 @@
 PORTNAME=	vulkan-headers
 DISTVERSIONPREFIX=	v
 DISTVERSION=	1.3.238
+PORTREVISION=	1
 CATEGORIES=	graphics
 
 MAINTAINER=	jbeich@FreeBSD.org
@@ -16,6 +17,10 @@ GH_PROJECT=	Vulkan-Headers
 STRIP=		# nothing to strip
 NO_ARCH=	yes
 
+post-extract:
+# genvk.py requires docgenerator.py from Vulkan-Docs, so drop useless shebang
+	@${FIND} ${WRKSRC}/registry -name \*.py -exec ${REINPLACE_CMD} -i '' '/^#!/d' {} +
+
 post-patch:
 # XXX Drop after FreeBSD 12.* EOL around 2024-06-30
 	@if [ -L /usr/include/sched.h ]; then \