Update README with correct Node version (#515)

Closes #514

Signed-off-by: Seth Vargo <seth@sethvargo.com>

Author: sethvargo

README.md

@@ -39,7 +39,7 @@ support](https://cloud.google.com/support).**
     gha-creds-*.json
     ```
 
--   This action runs using Node 20. Use a [runner
+-   This action runs using Node 24. Use a [runner
     version](https://github.com/actions/virtual-environments) that supports this
     version of Node or newer.