fix(screengrab): don't try grim on non-wlroots #80

Job	Run time
Test documentation build	42s
Lint & Test (macos-12)	5m 15s
Test Briefcase build (macos-12)	3m 32s
Lint & Test (windows-2022)	3m 32s
CodeQL (javascript)	1m 18s
Test Briefcase build (windows-2022)	5m 35s
CodeQL (python)	2m 21s
Test Briefcase build (ubuntu-22.04)	3m 7s
Lint & Test (ubuntu-22.04)	1m 26s
Test Python package build (macos-12)	2m 57s
Test Python package build (windows-2022)	1m 22s
Test Python package build (ubuntu-22.04)	19s
Deploy github pages	0s
Upload coverage	0s
Briefcase build & draft release	0s
Publish to PyPi	0s
	31m 26s

Provide feedback