Bump third_party/pigweed/repo from `ea93eb5` to `8a6f44e` #265

Job	Run time
Unit / Integration Tests (main)	15m 7s
Unit / Integration Tests (clang)	13m 37s
Unit / Integration Tests (mbedtls)	13m 47s
Unit / Integration Tests (rotating_device_id)	14m 5s
Unit / Integration Tests (icd)	43m 56s
	1h 40m 32s

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