devel/rubygem-aws-sdk-memorydb: Update to 1.18.0

Changes:	https://github.com/aws/aws-sdk-ruby/blob/version-3/gems/aws-sdk-memorydb/CHANGELOG.md

devel/rubygem-aws-sdk-memorydb/Makefile

 PORTNAME=	aws-sdk-memorydb
-PORTVERSION=	1.17.0
+PORTVERSION=	1.18.0
 CATEGORIES=	devel rubygems
 MASTER_SITES=	RG
 

devel/rubygem-aws-sdk-memorydb/distinfo

-TIMESTAMP = 1688902661
-SHA256 (rubygem/aws-sdk-memorydb-1.17.0.gem) = a077b14a1518f424a9990e30f8b34062568e5a2b0c4cc69140c53627fa7212e7
-SIZE (rubygem/aws-sdk-memorydb-1.17.0.gem) = 54784
+TIMESTAMP = 1689399363
+SHA256 (rubygem/aws-sdk-memorydb-1.18.0.gem) = 106d629164870214ad51baab7e9eeac92a5a385531e9116d674cc1fcb508cad2
+SIZE (rubygem/aws-sdk-memorydb-1.18.0.gem) = 54784