add .gitattributes that ignores lit #2

Job	Run time
unit-tests (ubuntu-latest, Release)	18m 51s
unit-tests (macos-latest, Release)	32m 32s
unit-tests (ubuntu-latest, Debug)	18m 51s
benchmarks (skip-run) (macos-latest, Release)	3m 13s
unit-tests (macos-latest, Debug)	29m 26s
benchmarks (skip-run) (ubuntu-latest, Debug)	3m 1s
benchmarks (skip-run) (macos-latest, Debug)	2m 48s
benchmarks (skip-run) (ubuntu-latest, Release)	2m 52s
	1h 51m 34s

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