Support terraform 0.14+

[pdecat]

This PR adds support for terraform 0.14.

Note: it is considered a "best practice" to not define upper limits for terraform core version in reusable modules:

Terraform Core and Provider Versions

Reusable modules should constrain only their minimum allowed versions of Terraform and providers, such as >= 0.12.0. This helps avoid known incompatibilities, while allowing the user of the module flexibility to upgrade to newer versions of Terraform without altering the module.

See https://www.terraform.io/docs/configuration/version-constraints.html#terraform-core-and-provider-versions

[bharathkkb]

Reusable modules should constrain only their minimum allowed versions of Terraform and providers, such as >= 0.12.0. This helps avoid known incompatibilities, while allowing the user of the module flexibility to upgrade to newer versions of Terraform without altering the module.

@morgante thoughts on this? This would prevent us from having to bump these each time and we can keep constraining the lower bounds as we include new features.

[morgante]

I think it's reasonable to drop the upper version constraint. We can restore it in cases where we know the module to be incompatible but I'm fine with being permissive by default.

[pdecat]

Should I go ahead and drop the upper version constraint like in https://github.com/terraform-google-modules/terraform-google-project-factory/pull/505/files ?

[morgante]

@pdecat Yes please do.

[pdecat]

Done.

Note: some files have >= 0.12 instead of >= 0.12.6, is that normal?

[morgante]

Likely they worked with any 0.12 version, this looks fine thanks!

[caarlos0]

any plans for a release?