Bump third_party/pigweed/repo from `90d97fa` to `cf32519` #1471

Job	Run time
Build on Darwin (clang, python_lib, simulated)	1h 2m 38s
Build on Linux (fake, gcc_release, clang, simulated)	1h 20m 35s
Build on Linux (gcc_debug)	43m 5s
Build on Linux (python_lib)	17m 24s
Build on Linux (python lighting-app)	6m 31s
Build on Linux (coverage)	9m 24s
	3h 39m 37s

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