private static Future<String> retrieveLatestVersionAsync() {
		if (versionCheckResult == null) {
			versionCheckResult = Executors.newSingleThreadExecutor().submit(VersionChecker::retrieveLatestVersion);
		}
		return versionCheckResult;
	}
Checks if we're running the latest version of JBang by comparing its version
against the latest version on GitHub.
src/main/java/dev/jbang/util/VersionChecker.java