Bump third_party/pigweed/repo from `1f12d06` to `d1e7bba` #969

Job	Run time
Build on Linux (fake, gcc_release, clang, simulated)	1h 44m 26s
Build on Linux (gcc_debug)	1h 13m 0s
Build on Linux (python_lib)	2m 1s
Build on Darwin (clang, python_lib, simulated)	3m 24s
Build on Linux (coverage)	16m 1s
Build on Linux (python lighting-app)	1m 49s
	3h 20m 41s

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