Tests

Bump third_party/pigweed/repo from `9e4bfb9` to `b12f7f8` #888

Job	Run time
REPL Tests - Darwin	0s
Test Suites - Linux (no-ble-tsan-clang)	12m 43s
Test Suites - Darwin (no-ble-asan-clang)	28m 24s
REPL Tests - Linux	11m 57s
	53m 4s

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