Deal with GHA deprecation warnings

[DMRobertson]

See matrix-org/synapse#14203 for more context.

The warnings I have in mind are e.g. https://github.com/matrix-org/synapse/actions/runs/4936859583

There are two categories of warnings. First:

Node.js 12 actions are deprecated. Please update the following actions to use Node.js 16:

• actions/github-script@v5

That comes from matrix-org/pr-details-action@v1.1. The warning should be fixed by #5, which pulls in matrix-org/pr-details-action#4.

• nwtgck/actions-netlify@f517512

Merging #8 should fix this, which pulls in nwtgck/actions-netlify#847.

Second:

The set-output command is deprecated and will be disabled soon.

https://github.com/matrix-org/synapse/actions/runs/4936859583/jobs/8824910967#step:3:30 is probably the easiest way to see where these come from.

• Update bobheadxi/deployments action to v1.4.0 #7 would cover the warnings about bobheadxi/deployments (see Warning: The set-output command is deprecated and will be disabled soon bobheadxi/deployments#123 and Bump actions/core bobheadxi/deployments#124)
• the rest should be covered by Update nwtgck/actions-netlify action to v2 #8.

I am happy to do this.

[DMRobertson]

I am happy to do this.

I was going to PR the changes, but I think merging #5, #7, #8 should fix this. @t3chguy would it be possible to merge those and release a new version of this action? (If it's any easier, I'm happy to do so if you prefer and are willing to grant me write access to the repository.)

[t3chguy]

@DMRobertson https://github.com/matrix-org/netlify-pr-preview/releases/tag/v2

[DMRobertson]

Thank you!!