runningVersion method
Returns the current version of the running build daemon.
Null if one isn't running.
Implementation
Future<String?> runningVersion() async {
final versionFile = File(
versionFilePath(_workingDirectory, daemonSharedPath: _daemonSharedPath),
);
if (!await waitForFile(versionFile)) return null;
return versionFile.readAsStringSync();
}