Bugfix add mode 0600 to netplan config file

[lanefu]

Description

newer netplan on Debian Sid errored because of file permission being too open. Added defaults driven attribute to specify mode when rendering template. Remediates error message below:

{"changed": true, "cmd": ["netplan", "generate"], "delta": "0:00:01.119055", "end": "2023-08-27 01:58:23.988600", "msg": "non-zero return code", "rc": 1, "start": "2023-08-27 01:58:22.869545", "stderr": "\n** (generate:2668): WARNING **: 01:58:23.846: Permissions for /etc/netplan/armbian-default.yaml are too open. Netplan configuration should NOT be accessible by others.\n/etc/netplan/armbian-default.yaml:3:12: Error in network definition: unknown renderer ''\n  renderer: \n           ^", "stderr_lines": ["", "** (generate:2668): WARNING **: 01:58:23.846: Permissions for /etc/netplan/armbian-default.yaml are too open. Netplan configuration should NOT be accessible by others.", "/etc/netplan/armbian-default.yaml:3:12: Error in network definition: unknown renderer ''", "  renderer: ", "           ^"], "stdout": "", "stdout_lines": []}

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Chore (non-breaking change that does not add functionality or fix an issue)

Checklist:

• [x] I have read the CONTRIBUTING document.
• [ ] I have run the pre-merge tests locally and they pass.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.