CI/CD

refactor(gui): pull dbus methods out; introduce jeepney #17

Job	Run time
Test Briefcase build (macos-12)	3m 21s
Test Briefcase build (windows-2022)	4m 31s
Lint & Test (macos-12)	2m 38s
Test Python package build (macos-12)	28s
Test Briefcase build (ubuntu-22.04)	3m 22s
Lint & Test (windows-2022)	3m 13s
CodeQL (javascript)	58s
Test Python package build (windows-2022)	1m 0s
Lint & Test (ubuntu-22.04)	1m 35s
CodeQL (python)	2m 9s
Test Python package build (ubuntu-22.04)	20s
Upload coverage	4s
Briefcase build & draft release	0s
Publish to PyPi	0s
Deploy github pages	0s
	23m 39s

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