Bump third_party/mbedtls/repo from `5bc604f` to `42c82ae` #568

Job	Run time
REPL Tests - Darwin	0s
REPL Tests - Linux	54m 23s
Test Suites - Darwin (no-ble-asan-clang)	1h 22m 13s
Test Suites - Linux (no-ble-tsan-clang)	1h 28m 24s
Test Suites - Darwin (no-ble-tsan-clang)	1h 43m 23s
	5h 28m 23s

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