Update to use PAT to avoid rate limits and update build environment

[clue]

This changeset updates the build script to use a PAT secret to avoid secondary rate limits and updates the build environment. Each PAT has a rate limit of 5000 requests/h while the GITHUB_TOKEN has a rate limit of 1000 requests/h (https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api?apiVersion=2022-11-28#primary-rate-limit-for-github_token-in-github-actions).

I've already assigned a read-only PAT for the @reactphp-bot user for this repository. This secret should be available to the build script after this PR is merged. This means that the PR may currently fail to build, but should work regardless once merged. I've assigned the same PAT to my fork to confirm this works as expected. Once merged, the build should now work again and finally deploy all releases published since #67 was reported.

Resolves / closes #67
Builds on top of #53 and #65

[clue]

Confirmed to work by restarting the build for the merge commit, the website now builds successfully again. Not sure why the merge commit didn't pass originally, but we'll keep an eye on this until we get to improve the build process to no longer run into any rate limiting issues.