Use actions running on `node16`

[michalinacienciala]

Node 12 has been out of support since April 2022, as a result GitHub has started the deprecation process of Node 12 for GitHub Actions. They plan to migrate all actions to run on Node16 by Summer 2023. Some of the GH Marketplace actions that we've been using in our workflows were running on node12, but have already published new versions running on node16. We're updating those actions to the latest versions.

Read more on https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.

In this PR we also change the extension of the workflow file to .yml to be consistent with names of other workflows in different repositories in the threshold-network project.

[github-actions[bot]]

Preview uploaded to https://preview.threshold.network/node16/index.html.

[nkuba]

@michalinacienciala please resolve conflicts.

[michalinacienciala]

@michalinacienciala please resolve conflicts.

@nkuba, done!

[github-actions[bot]]

Preview uploaded to https://preview.threshold.network/node16/index.html.