Bump third_party/pigweed/repo from `9504c03` to `8b5d45a` #1126

Job	Run time
Unit / Integration Tests (main)	1m 5s
Unit / Integration Tests (clang)	2m 28s
Unit / Integration Tests (mbedtls)	30s
Unit / Integration Tests (rotating_device_id)	23s
	4m 26s

Provide feedback