fix(ci): add environment to docs-preview

[jsjoeio]

This PR updates the docs-preview.yaml workflow to use an environment which should have the correct secrets for deploying a docs preview.

Fixes #4027

[jsjoeio]

I'm not sure what is going wrong here:

I'll need to further investigate

[jsjoeio]

@jawnsy and I discussed this. We're not sure why it's failing. We think merging it might fix so we're going to try that.

[codecov]

Codecov Report

Merging #4677 (f18474f) into main (0034808) will not change coverage.
The diff coverage is n/a.

❗ Current head f18474f differs from pull request most recent head 39b2ac8. Consider uploading reports for the commit 39b2ac8 to get more accurate results

@@           Coverage Diff           @@
##             main    #4677   +/-   ##
=======================================
  Coverage   69.10%   69.10%           
=======================================
  Files          29       29           
  Lines        1638     1638           
  Branches      341      341           
=======================================
  Hits         1132     1132           
  Misses        430      430           
  Partials       76       76           

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