Add OpenTofu support

[denis256]

Describe the solution you'd like
Add support for running action with OpenTofu instead of Terraform.

While Terraform will continue to be a supported option, additional should be added additional input for OpenTofu version, and an exclusion check to support only one version input(OpenTofu or Terraform)

Describe alternatives you've considered
N/A

Additional context
https://opentofu.org/blog/the-opentofu-fork-is-now-available

[kvendingoldo]

At this moment if you need to have a support of Terraform as well as OpenTofu (and Terragrunt :) ) in one tool you can use https://github.com/tofuutils/tenv which my team wrote some months ago. A lot of users switched to that tool to unify version management in the world of Terraform.

You're welcome to open any issues or contribute to tenv.