move all of the hosts from 192.168.67.x to 192.168.56.x

The VirtualBox documentation says this is the network to use for host-only
networking.

morph/grid/local/Vagrantfile

@@ -23,7 +23,12 @@ Vagrant.configure("2") do |config|
     #   v.memory = 4096
     # end
 
-    config.vm.network "private_network", ip: "192.168.67.21"
+    # Assign a static IP address inside the VirtualBox host-only (Vagrant
+    # calls it "private") network.  The address must be in the range
+    # VirtualBox allows.
+    # https://www.virtualbox.org/manual/ch06.html#network_hostonly says some
+    # things about this.
+    config.vm.network "private_network", ip: "192.168.56.21"
     # Add self signed SSL key for zkap-issuer:
     config.vm.provision "file", source: "private-keys/payments-localdev-ssl", destination: "/tmp/payments-localdev-ssl"
     config.vm.provision "shell", inline: "sudo mkdir -p /var/lib/letsencrypt/live/payments.localdev/"
@@ -35,7 +40,7 @@ Vagrant.configure("2") do |config|
     config.vm.box = "esselius/nixos"
     config.vm.box_version = "20.09"
     config.vm.box_check_update = false
-    config.vm.network "private_network", ip: "192.168.67.22"
+    config.vm.network "private_network", ip: "192.168.56.22"
   end
 
   config.vm.define "storage2.localdev" do |config|
@@ -43,7 +48,7 @@ Vagrant.configure("2") do |config|
     config.vm.box = "esselius/nixos"
     config.vm.box_version = "20.09"
     config.vm.box_check_update = false
-    config.vm.network "private_network", ip: "192.168.67.23"
+    config.vm.network "private_network", ip: "192.168.56.23"
   end
 
   config.vm.define "monitoring.localdev" do |config|
@@ -51,7 +56,7 @@ Vagrant.configure("2") do |config|
     config.vm.box = "esselius/nixos"
     config.vm.box_version = "20.09"
     config.vm.box_check_update = false
-    config.vm.network "private_network", ip: "192.168.67.24"
+    config.vm.network "private_network", ip: "192.168.56.24"
   end
 
   # To make the VMs assign the static IPs to the network interfaces we need a rebuild:
@@ -60,7 +65,7 @@ Vagrant.configure("2") do |config|
 
   config.trigger.after :up do |trigger|
     trigger.info = "Hostname and IP address this host actually uses:"
-    trigger.run_remote = {inline: "echo `hostname` `ifconfig | egrep -o '192.168.67.[0-9]* '`"}
+    trigger.run_remote = {inline: "echo `hostname` `ifconfig | egrep -o '192.168.56.[0-9]* '`"}
   end
 
 end