Fix `test_window_state_assignment` testbed on macOS-arm64 #7344

Job	Run time
Check towncrier / Towncrier Checks	31s
Pre-commit checks / Pre-commit Checks	42s
Package Toga (cocoa) / Create Python Package	35s
Package Toga (demo) / Create Python Package	24s
Package Toga (core) / Create Python Package	36s
Package Toga (android) / Create Python Package	18s
Package Toga (dummy) / Create Python Package	22s
Package Toga (gtk) / Create Python Package	23s
Package Toga (iOS) / Create Python Package	49s
Package Toga (textual) / Create Python Package	56s
Package Toga (toga) / Create Python Package	25s
Package Toga (web) / Create Python Package	16s
Package Toga (winforms) / Create Python Package	31s
Test core (macos-latest, 3.9)	1m 25s
Test core (macos-latest, 3.10)	1m 9s
Test core (macos-latest, 3.11)	50s
Test core (macos-latest, 3.12)	1m 7s
Test core (macos-latest, 3.13)	2m 26s
Test core (ubuntu-latest, 3.9)	1m 56s
Test core (ubuntu-latest, 3.10)	2m 25s
Test core (ubuntu-latest, 3.11)	58s
Test core (ubuntu-latest, 3.12)	1m 0s
Test core (ubuntu-latest, 3.13)	1m 29s
Test core (windows-latest, 3.9)	1m 56s
Test core (windows-latest, 3.10)	1m 38s
Test core (windows-latest, 3.11)	1m 40s
Test core (windows-latest, 3.12)	1m 41s
Test core (windows-latest, 3.13)	2m 26s
Coverage	36s
Testbed (macOS-x86_64)	7m 42s
Testbed (macOS-arm64)	6m 27s
Testbed (windows)	8m 19s
Testbed (linux-x11)	5m 5s
Testbed (linux-wayland)	5m 23s
Testbed (android)	9m 2s
Testbed (iOS)	7m 0s
Testbed (textual-linux)	48s
Testbed (textual-macOS)	58s
Testbed (textual-windows)	2m 7s
	1h 24m 21s

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