Release 0.17.4

# History

## 0.17.4

Install/update via the bootstrap script:

```shell
wget https://raw.githubusercontent.com/dokku/dokku/v0.17.4/bootstrap.sh
sudo DOKKU_TAG=v0.17.4 bash bootstrap.sh
```

### New Features

- #3575: @josegonzalez Add a way to cleanup apps for specific schedulers

contrib/dokku-installer.py

@@ -10,7 +10,7 @@ import subprocess
 import sys
 import threading
 
-VERSION = 'v0.17.3'
+VERSION = 'v0.17.4'
 
 hostname = ''
 try: