Bump third_party/mbedtls/repo from `0dc3ed0` to `56fd26c` #1249

Job	Run time
Unit / Integration Tests (main)	13m 14s
Unit / Integration Tests (clang)	13m 25s
Unit / Integration Tests (mbedtls)	13m 35s
Unit / Integration Tests (rotating_device_id)	13m 43s
Unit / Integration Tests (icd)	23m 20s
	1h 17m 17s

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