Bump third_party/pigweed/repo from `ea93eb5` to `8a6f44e` #266

Job	Run time
Unit / Integration Tests (main)	14m 39s
Unit / Integration Tests (clang)	12m 37s
Unit / Integration Tests (mbedtls)	15m 26s
Unit / Integration Tests (rotating_device_id)	15m 35s
Unit / Integration Tests (icd)	45m 1s
	1h 43m 18s

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