Fix incorrect govultr delete method for VPC2

[optik-aper]

Description

Fix incorrect govultr delete method for VPC2. Previously this error was thrown on any and all VPC2 deletes:

Error: error deleting vpc2 : {"error":"Invalid private network ID.","status":404}
exit status 1

Testing instructions

Make sure a VPC2 can be deleted

go run main.go vpc2 delete UUID_HERE

Related Issues

Fixes #424

Checklist:

• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you linted your code locally prior to submission?
• Have you successfully ran tests with your changes locally?

[github-actions]

Unit Tests and Coverage

Show Output

?   	github.com/vultr/vultr-cli/v3	[no test files]

Pusher: @optik-aper, Action: pull_request_target