Fix tables losing their cell borders after upgrading to Qt 6.8 #100

Job	Run time
build (ubuntu-22.04, Debug, static, 5.15)	1m 12s
build (ubuntu-22.04, Debug, static, 6.6.0)	1m 38s
build (ubuntu-22.04, Debug, dynamic, 5.15)	1m 18s
build (ubuntu-22.04, Debug, dynamic, 6.6.0)	1m 34s
build (ubuntu-22.04, Release, static, 5.15)	48s
build (ubuntu-22.04, Release, static, 6.6.0)	51s
build (ubuntu-22.04, Release, dynamic, 5.15)	43s
build (ubuntu-22.04, Release, dynamic, 6.6.0)	59s
build (windows-2022, Debug, static, 5.15)	3m 1s
build (windows-2022, Debug, static, 6.6.0)	2m 22s
build (windows-2022, Debug, dynamic, 5.15)	2m 48s
build (windows-2022, Debug, dynamic, 6.6.0)	4m 8s
build (windows-2022, Release, static, 5.15)	1m 40s
build (windows-2022, Release, static, 6.6.0)	1m 37s
build (windows-2022, Release, dynamic, 5.15)	1m 13s
build (windows-2022, Release, dynamic, 6.6.0)	2m 29s
build (macos-13, Debug, static, 5.15)	2m 42s
build (macos-13, Debug, static, 6.6.0)	4m 22s
build (macos-13, Debug, dynamic, 5.15)	1m 36s
build (macos-13, Debug, dynamic, 6.6.0)	5m 36s
build (macos-13, Release, static, 5.15)	1m 16s
build (macos-13, Release, static, 6.6.0)	1m 52s
build (macos-13, Release, dynamic, 5.15)	1m 28s
build (macos-13, Release, dynamic, 6.6.0)	3m 10s
build (ubuntu-22.04, Release, dynamic, 6.6.0, llvm, shiboken6-generator==6.6.0 pyside6==6.6.0)	1m 39s
	52m 2s

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