"I should be able to install a package using Synaptic" step is fragile
_Originally created by @intrigeri on [#10900 (Redmine)](https://public-redmine-archive.tails.boum.org/code/issues/10900)_
```
Scenario: Install packages using Synaptic # features/apt.feature:23
When I start Synaptic # features/step_definitions/apt.rb:52
And I update APT using Synaptic # features/step_definitions/apt.rb:31
Then I should be able to install a package using Synaptic # features/step_definitions/apt.rb:37
FindFailed: can not find SynapticChangesAppliedPrompt.png on the screen.
Line ?, in File ? (RuntimeError)
features/apt.feature:26:in `Then I should be able to install a package using Synaptic'
```
… while the screenshot does show the “Changes applied” dialog. Timeout
bump?
Parent Task: tails/tails#10288
### Related issues
- [x] **Blocked by** tails/tails#10441
issue