Release 0.22.4

# History

## 0.22.4

Install/update via the bootstrap script:

```shell
wget https://raw.githubusercontent.com/dokku/dokku/v0.22.4/bootstrap.sh
sudo DOKKU_TAG=v0.22.4 bash bootstrap.sh
```

### Bug Fixes

- #4274: @josegonzalez Use correct warning message for deprecated code

### New Features

- #4273: @josegonzalez Upgrade to golang 1.15

### Refactors

- #4275: @josegonzalez Add calls to verify app name in subcommands

### Documentation

- #4272: @josegonzalez Correct help output for ssh-keys command

### Tests

- #4276: @josegonzalez Upgrade version of plugn used in tests

docs/assets/style.css

@@ -39,13 +39,13 @@ h1 {
   font-size: 1.6em;
 }
 .header .navbar-brand a {
-  background-image: url(https://cdn.jsdelivr.net/gh/dokku/dokku@v0.22.3/docs/assets/dokku.png);
+  background-image: url(https://cdn.jsdelivr.net/gh/dokku/dokku@v0.22.4/docs/assets/dokku.png);
   text-indent: 40px;
 }
 .blurb {
   color: #424242;
   background-color: #ededed;
-  background-image: url(https://cdn.jsdelivr.net/gh/dokku/dokku@v0.22.3/docs/assets/gplaypattern.png);
+  background-image: url(https://cdn.jsdelivr.net/gh/dokku/dokku@v0.22.4/docs/assets/gplaypattern.png);
   padding: 45px 0;
   text-align: center;
 }