vagrant: use pyenv in freebsd64 VM

... so we have the same python 3.6.9 based build as in the macOS and Linux VM.

Vagrantfile

@@ -336,7 +336,9 @@ Vagrant.configure(2) do |config|
     b.ssh.shell = "sh"
     b.vm.provision "fs init", :type => :shell, :inline => fs_init("vagrant")
     b.vm.provision "packages freebsd", :type => :shell, :inline => packages_freebsd
-    b.vm.provision "build env", :type => :shell, :privileged => false, :inline => build_sys_venv("freebsd64")
+    b.vm.provision "install pyenv", :type => :shell, :privileged => false, :inline => install_pyenv("freebsd64")
+    b.vm.provision "install pythons", :type => :shell, :privileged => false, :inline => install_pythons("freebsd64")
+    b.vm.provision "build env", :type => :shell, :privileged => false, :inline => build_pyenv_venv("freebsd64")
     b.vm.provision "install borg", :type => :shell, :privileged => false, :inline => install_borg(true)
     b.vm.provision "install pyinstaller", :type => :shell, :privileged => false, :inline => install_pyinstaller()
     b.vm.provision "build binary with pyinstaller", :type => :shell, :privileged => false, :inline => build_binary_with_pyinstaller("freebsd64")