chore: Automatically updates Terraform version used in repository and test-suite

[maastha]

Description

Automatically updates Terraform version used in repository and test-suite.

This job will create a PR like https://github.com/mongodb/terraform-provider-mongodbatlas/pull/2756 when a change in supported TF versions is detected.

Link to any related issue(s): CLOUDP-243394

Type of change:

• [ ] Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• [ ] New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR. A migration guide must be created or updated if the new feature will go in a major version.
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected). Please, add the "breaking change" label to the PR. A migration guide must be created or updated.
• [ ] This change requires a documentation update
• [ ] Documentation fix/enhancement

Required Checklist:

• [ ] I have signed the MongoDB CLA
• [ ] I have read the contributing guides
• [ ] I have checked that this change does not generate any credentials and that they are NOT accidentally logged anywhere.
• [ ] I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• [ ] I have added any necessary documentation (if appropriate)
• [ ] I have run make fmt and formatted my code
• [ ] If changes include deprecations or removals I have added appropriate changelog entries.
• [ ] If changes include removal or addition of 3rd party GitHub actions, I updated our internal document. Reach out to the APIx Integration slack channel to get access to the internal document.

Further comments

[lantoli]

hi @maastha cc @EspenAlbert , some context that can help: Current value for TF_VERSION_LATEST is 1.9.x, so scripts/tools/GHA/features using it will pick the latest patch for 1.9, it's currently 1.9.8.

However there are some tools/features like .tool-versions, or generate-doc.sh and generate-docs-all.sh (for tfplugindocs generate) that need an explicit version like 1.9.8, 1.9.x can not be used in these cases. So in that case i think we should use the latest patch to make it equivalent to tools using the .X notation. E.g. I think it's better to have now 1.9.8 in .tool-versions instead of 1.9.0 so we can anticipate problems in the latest published TF version. Similarly for tfplugindocs generate tool.

Additionally I think it's better to use TF_VERSION_LATEST directly when format 1.9.x can be used, instead of having explicitly 1.9.x in those tools, so we don't need to update many files when a major TF version is released. ( note that TF_VERSION_LATEST doesn't need to be updated for minor releases)

edit: i see TF_VERSION_LATEST is used in 4 places, i'm ok if we want to delete the var and use 1.9.x directly, and update them when a major release comes. But I still think we should update patches in tools not supporting .X notation.