build: update rules_browsers digest to 508168a #2045

Job	Run time
list	19s
workflow (modules-builder-tests)	1m 56s
workflow (build-cli)	1m 41s
workflow (build-unit-tests)	2m 13s
workflow (devkit-core-tests)	1m 26s
workflow (devkit-core-tests-rerun)	1m 24s
	8m 59s

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