It seems the SpeedTestForInfluxDB project has been retired by its owner and replaced with a new project called SpeedMon. See here: https://github.com/barrycarey/Speedtest-for-InfluxDB-and-Grafana/issues/46#issuecomment-933066819
Maybe it's time for me to learn how to make an Unraid template from scratch for SpeedMon but kind of hoping somebody else might have the time and experience to do it 🙂