Can't go through validate hook with an pkrvars file as input

# 💡 Summary #

It would be great to allow the args to specify the path to the pkrvars file to be used when validating the packer files

## Motivation and context ##

as of today the basic command with packer works :
packer validate -var-file="inputs/dev.pkrvars.hcl" .

However when using the pre-commit hook validate there is no way to map with the righ pkrvars file.
This would be useful because...

## Implementation notes ##

Please provide details for implementation, such as:

an example would be :

repos:
- repo: https://github.com/cisagov/pre-commit-packer
rev: v0.0.2
hooks:
- id: packer_fmt
- id: packer_validate
args:
- '--args=--var-file="inputs/dev.pkrvars.hcl'

## Acceptance criteria ##

How do we know when this work is done?

- [ ] Ability to run validate by providing a pkrvars.hcl file as input