Fix `test_window_state_assignment` testbed on macOS-arm64 #7363

Job	Run time
Pre-commit checks / Pre-commit Checks	36s
Check towncrier / Towncrier Checks	42s
Package Toga (cocoa) / Create Python Package	24s
Package Toga (core) / Create Python Package	28s
Package Toga (android) / Create Python Package	16s
Package Toga (dummy) / Create Python Package	32s
Package Toga (demo) / Create Python Package	22s
Package Toga (gtk) / Create Python Package	15s
Package Toga (iOS) / Create Python Package	24s
Package Toga (textual) / Create Python Package	15s
Package Toga (toga) / Create Python Package	23s
Package Toga (web) / Create Python Package	17s
Package Toga (winforms) / Create Python Package	19s
Test core (macos-latest, 3.9)	1m 14s
Test core (macos-latest, 3.10)	1m 28s
Test core (macos-latest, 3.11)	43s
Test core (macos-latest, 3.12)	1m 7s
Test core (macos-latest, 3.13)	51s
Test core (ubuntu-latest, 3.9)	49s
Test core (ubuntu-latest, 3.10)	48s
Test core (ubuntu-latest, 3.11)	47s
Test core (ubuntu-latest, 3.12)	59s
Test core (ubuntu-latest, 3.13)	1m 15s
Test core (windows-latest, 3.9)	1m 23s
Test core (windows-latest, 3.10)	1m 53s
Test core (windows-latest, 3.11)	1m 33s
Test core (windows-latest, 3.12)	1m 48s
Test core (windows-latest, 3.13)	2m 38s
Coverage	37s
Testbed (macOS-x86_64)	8m 31s
Testbed (macOS-arm64)	7m 9s
Testbed (windows)	7m 28s
Testbed (linux-x11)	4m 57s
Testbed (linux-wayland)	5m 36s
Testbed (android)	9m 31s
Testbed (iOS)	8m 25s
Testbed (textual-linux)	49s
Testbed (textual-macOS)	1m 3s
Testbed (textual-windows)	1m 58s
	1h 20m 33s

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