virtualbox.yml

---
apt_upgrade_file: virtualbox_upgrade.yml

VMware.yml

---
apt_upgrade_file: vmware_tools_upgrade.yml

webhost.yml

---
- hosts: webhost.dev
  user: vagrant
  sudo: yes
  vars_files:
    - "vars/{{ ansible_virtualization_type }}.yml"
  tasks:

    - include: {{ apt_upgrade_file }}

$ ansible-playbook webhost.yml

ERROR: Syntax Error while loading YAML script, webhost.yml
Note: The error may actually appear before this position: line 9, column 17


    - include: {{ apt_upgrade_file }}