build: update rules_browsers digest to 6a699bf #8925

Job	Run time
lint	6s
build-e2e-windows	7s
build	7s
e2e-windows	1s
publish-snapshots	1s
e2e-snapshots	1s
test	1s
Browser Compatibility Tests	1s
e2e	1s
e2e-package-managers	1s
	27s

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