Update mk/platform/Darwin.mk

[Brook Milligan <brook%nmsu.edu@localhost>]

I have just updated my Mac to 13.5.1 (Ventura) and Xcode to 14.3.1 (with an SDK version of 13.3).

This is beyond the mapping in mk/platform/Darwin.mk, which ends at ${OSX_VERSION} == 13.4.

I would like to comit the following patch to cover this case.  

Please let me know if something else should be done.

Thanks a lot.

Cheers,
Brook

cvs diff: Diffing .
Index: Darwin.mk
===================================================================
RCS file: /cvsroot/pkgsrc/mk/platform/Darwin.mk,v
retrieving revision 1.128
diff -u -r1.128 Darwin.mk
--- Darwin.mk	28 May 2023 09:38:37 -0000	1.128
+++ Darwin.mk	20 Aug 2023 04:20:28 -0000
@@ -120,6 +120,7 @@
 OSX_SDK_MAP.13.2=	13.1
 OSX_SDK_MAP.13.3=	13.3
 OSX_SDK_MAP.13.4=	13.3
+OSX_SDK_MAP.13.5=	13.3
 #
 # If the user has set MACOSX_DEPLOYMENT_TARGET (ideally at bootstrap time) to
 # select a specific SDK then we prefer that.