CI: Update first-party GitHub Actions to v4

[RytoEX]

Description

CI: Update first-party GitHub Actions to v4

GitHub Actions has deprecated actions based on node16. The v4 actions are based on node20. Replace first-party v2/v3 actions with their v4 counterparts.

GitHub Actions has deprecated actions based on node12 and forces them to run on node16, which is also deprecated. Update to v4 actions to avoid warnings on CI.

See:

• https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/
• https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/

Motivation and Context

Want less CI warnings and don't want CI to stop working when node12/node16 are disabled.

How Has This Been Tested?

This is on CI. obs-deps, obs-studio, obs-browser, and obs-plugintemplate have had successful runs with updated first-party actions.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• Other Enhancement (anything not applicable to what is listed)

Checklist:

• I have read the Contributing Guidelines.
• All commit messages are properly formatted and commits squashed where appropriate.
• My code is not on master or a release/* branch.
• The code has been tested.
• I have included updates to all appropriate documentation.

[RytoEX]

It does look like sometimes we use lowercase ci: here for a prefix. Let me know if this needs to be changed.

[tt2468]

I'm not too picky about commit prefixes for stuff like this, so that's fine.