SpringBoot Wait until spring-boot.rb file is available when updating Homebrew tap

When syncing to Central, we check that the core spring-boot jar is available:

https://github.com/spring-projects/spring-boot/blob/9ff53f8c24d365fd47d1a112acafddd268d6b125/.github/actions/sync-to-maven-central/action.yml#L40-L50

With the way that Central's CDN works, the availability of this jar isn't a guarantee that all other artifacts will be available immediately. In the 3.3.2 release, this caused the spring-boot.rb file that defines the Homebrew formula for Boot's CLI to be corrupted. We should add some similar wait logic to the action that updates the Homebrew tap with the new formula.