Build/Test Tools: Update third-party GitHub Actions to latest versions.

Updated actions:
- `actions/cache`
- `actions/github-script`
- `actions/setup-node`
- `bubkoo/welcome-action`
- `shivammathur/setup-php`
- `slackapi/slack-github-action`

See #55652.
Built from https://develop.svn.wordpress.org/trunk@53940


git-svn-id: http://core.svn.wordpress.org/trunk@53499 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53939';
+$wp_version = '6.1-alpha-53940';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.