Fix GitHub Action Condition

[sprankhub]

As can be seen here, the current condition on the GitHub Action "Terraform plan" does not work:

terraform/.github/workflows/terraform-plan.yml

Lines 14 to 22 in da5dfbe

	if: >
	${{
	github.event.issue.pull_request &&
	github.event.comment.body == '/plan' &&
	(
	github.event.comment.user.login == 'Vinai' ||
	github.event.comment.user.login == 'sprankhub'
	)
	}}

The action was executed on an issue comment, even though we only want to execute it on pull request comments with a certain text from certain authors. I checked the condition and it pretty much seems to use the same condition as shown in the docs.

[sprankhub]

This is a test comment to see if the fix actually works :)