Build/Test Tools: Update some NPM packages.

This updates the following packages to the latest versions. 

Updated packages:
- `check-node-version` from `4.0.1` to `4.0.3`.
- `node-sass` from `4.14.1` to `5.0.0`.
- `wait-on` from `3.3.0` to `5.2.1`.

See #51801.
Built from https://develop.svn.wordpress.org/trunk@49937


git-svn-id: http://core.svn.wordpress.org/trunk@49636 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.7-alpha-49936';
+$wp_version = '5.7-alpha-49937';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.