Replace deprecated set-output with GITHUB_OUTPUT

[yucheng11122017]

Resolves #9 and Resolves #12

As set-output and save-state is set to be deprecated, let's get rid of it before it is deprecated.
Markbind actions only uses set-output

Overview of changes
Change set-output to use GITHUB_OUTPUT instead.

Testing instructions

1. Make repo using markbind init or use existing repo.
2. Add fork-build.yml, fork-preview.yml and unpublish-preview.yml according to README in reusable workflows.
3. Change the uses to yucheng11122017/markbind-action/.github/workflows/{FILE_NAME}@replaceSetOutput for each of the above files
4. Create a new pull request to main branch (or change the name of branch in workflow to the branch you make a PR to)
5. Check logs that the PR number and PR URL of the deployed site is as expected.
6. Close PR to trigger unpublish-preview.yml
7. Check action logs to check that the correct URL is being torn down
8. Check that site is actually torn down by going to the site and seeing project not found error

Proposed commit message
Replace deprecated set-output with GITHUB_OUTPUT

[jovyntls]

Nice catch on the deprecations @yucheng11122017 :) I haven't tested it, but can we update the commit message to include a note on why we are doing this replacement?

[yucheng11122017]

Nice catch on the deprecations @yucheng11122017 :) I haven't tested it, but can we update the commit message to include a note on why we are doing this replacement?

I added deprecated hope thats ok!

[tlylt]

@yucheng11122017 do you have links to your tested repos/workflow runs? I think the syntax looks correct, I can take a second look at your testing to confirm.

[yucheng11122017]

Hi @tlylt,
this is the workflow for fork-preview.yml. Please note that there are some warnings about set-output as peter-evans/find-comment@v1 and peter-evans/create-or-update-comment@v1 is still using set-output, causing 4 warnings.

This is the workflow for unpublic-preview.yml. Similarly, there are the same errors.

[tlylt]

peter-evans/create-or-update-comment

possible to update our usage of those two actions?

[yucheng11122017]

peter-evans/create-or-update-comment

possible to update our usage of those two actions?

Yes sure. In this PR?

[tlylt]

peter-evans/create-or-update-comment

possible to update our usage of those two actions?

Yes sure. In this PR?

Yes pls

[yucheng11122017]

Hi @tlylt, updated in these two commits.

Please see the workflow for build fork, preview fork, unpublish site and action.yml