vagrant: macos: give more memory

sometimes the VM just got stuck (usually when building/testing openssl 3),
maybe more RAM helps?

Vagrantfile

@@ -395,7 +395,7 @@ Vagrant.configure(2) do |config|
   config.vm.define "macos1012" do |b|
     b.vm.box = "macos-sierra"
     b.vm.provider :virtualbox do |v|
-      v.memory = 4096 + $wmem
+      v.memory = 8192 + $wmem
       v.customize ['modifyvm', :id, '--ostype', 'MacOS_64']
       v.customize ['modifyvm', :id, '--paravirtprovider', 'default']
       v.customize ['modifyvm', :id, '--nested-hw-virt', 'on']