Add key expiration to tailscale_tailnet_key

[dizzzan]

What this PR does / why we need it:
Adds key expiration option to the tailscale_tailnet_key resource

Which issue this PR fixes
N/A

Special notes for your reviewer:
See tailscale/tailscale-client-go#34 for associated client change

[dizzzan]

@DentonGentry Haven't looked too closely at your CI setup, but does this depend on the published client pkg?

[DentonGentry]

I created a v1.7.0 release in tailscale-client-go. You should be able to update to that version of the module and try again:

go get tailscale/tailscale-client-go@v1.7.0
git add go.mod go.sum
git commit --amend -S
git push -f

[DentonGentry]

dependabot sent a PR to update this repo to 1.7. You'll need to rebase your PR to pull that change in:

git rebase main
git push -f

[dizzzan]

Didn't realize the docs were generated - should I remove my manual edits?

[DentonGentry]

Didn't realize the docs were generated - should I remove my manual edits?

Yes, please remove the docs changes. If we want to update the docstring we'd go back to the source document.

[davidsbond]

You'll need to install the tfplugindocs tool and then run go generate ./... which will update the documentation based on the code changes, which you can then commit. Might need to be added to the README

[davidsbond]

Please run terraform fmt on this example just so the indentation is correct.

[DentonGentry]

Great! This looks good, and the CI is happy.

[dizzzan]

@DentonGentry @davidsbond thank you both for the guidance, and for a great service! :)