That's the old and obsolete public testnet created by @blocktrades.
One you should use is that run currently by Steemit Inc.
API endpoint https://testnet.steemitdev.com/
Lately, it was re-initialized and currently there are no proposals there.
HF21 on a testnet is scheduled to 2019-07-09T17:00:00

Once it's on HF21 and I get some funds I will create few proposals.