Allow using GSSAPI auth for pg backend

[dequbed]

This is a very small change that just enabled GSSAPI authentication in the pg backend.

I'm not sure if you want the go.mod also added as commit which is why I have added it as a second commit. If you do want me to add in the PR I'll squash those two commits into one.

[hashicorp-cla]

All committers have signed the CLA.

[crw]

Thanks for this submission! The reason it has not been reviewed is due to the general hold on backend reviews (see CONTRIBUTING.md#state-storage-backends. I will update this PR if/when that is lifted. Thanks again for your submission!

[XDjackieXD]

Isn't this just an improvement to an existing backend rather than a new one? (the contributing guide only talks about new backends) Having to rely on building our own packages based on this PR is not ideal but we need this feature :/

[crw]

@remilapeyre for your review, if you please!

@XDjackieXD apologies, made a mistake when looking at this. It should have gone to the reviewer per https://github.com/hashicorp/terraform/blob/main/CODEOWNERS.

[remilapeyre]

Hi, I will review shortly and keep you updated.

[XDjackieXD]

Hi, I will review shortly and keep you updated.

Hi! Any news on this? We are still running our fork and would like to migrate back to the official packages of terraform :)

[XDjackieXD]

Any news on this?

[crw]

Hi @XDjackieXD, sorry no news. Gentle reminder @remilapeyre.