security/aws-c-cal: Update to 0.5.21

ChangeLog: https://github.com/awslabs/aws-c-cal/releases/tag/v0.5.21

security/aws-c-cal/Makefile

 PORTNAME=	aws-c-cal
 DISTVERSIONPREFIX=	v
-DISTVERSION=	0.5.20
+DISTVERSION=	0.5.21
 CATEGORIES=	security
 
 MAINTAINER=	eduardo@FreeBSD.org

security/aws-c-cal/distinfo

-TIMESTAMP = 1665406599
-SHA256 (awslabs-aws-c-cal-v0.5.20_GH0.tar.gz) = acc352359bd06f8597415c366cf4ec4f00d0b0da92d637039a73323dd55b6cd0
-SIZE (awslabs-aws-c-cal-v0.5.20_GH0.tar.gz) = 1615468
+TIMESTAMP = 1677747713
+SHA256 (awslabs-aws-c-cal-v0.5.21_GH0.tar.gz) = 525a84732cdd549842575502d59e10d2a10b23aa556a2318326e344be76bc6c8
+SIZE (awslabs-aws-c-cal-v0.5.21_GH0.tar.gz) = 1615573