lang/ruby24: update to 2.4.6, includes rubygems' security fix

https://www.ruby-lang.org/en/news/2019/04/01/ruby-2-4-6-released/

lang/ruby24/Portfile

@@ -4,8 +4,8 @@ PortSystem          1.0
 PortGroup           select 1.0
 
 name                ruby24
-version             2.4.5
-revision            2
+version             2.4.6
+revision            0
 
 categories          lang ruby
 maintainers         {kimuraw @kimuraw} openmaintainer
@@ -33,10 +33,10 @@ dist_subdir         ruby24
 #     /opt/local/lib/libruby.2.4.dylib
 patchfiles          patch-configure.diff
 
-checksums           md5 45d70a8bb9397d818795ffe992163d27 \
-                    rmd160 72478559b56856d77f2898148bfeb35f294c4dc1 \
-                    sha1 0e1f184556507c22bc59054496c0af7cf28fb188 \
-                    sha256 276c8e73e51e4ba6a0fe81fb92669734e741ccea86f01c45e99f2c7ef7bcd1e3
+checksums           md5 4abd13c50c1fc273a0a81a0ae74ed39f \
+                    rmd160 05dc7f36b31478bb61495553a74875eb49737b4a \
+                    sha1 b44b5c6637a69b3b95971b1937ecb583dc1de568 \
+                    sha256 909f360debed1f22fdcfc9f5335c6eaa0713198db4a6c13bab426f8b89b28b02
 
 use_parallel_build  no