feat: impl TryFrom str for Timestamp #499

Job	Run time
test (stable, ubuntu-latest, stable)	6m 17s
cross (i686-unknown-linux-gnu)	1m 22s
rustfmt	5s
msrv	1m 16s
test (beta, ubuntu-latest, beta)	6m 9s
cross (aarch64-unknown-linux-gnu)	1m 54s
test (nightly, ubuntu-latest, nightly)	4m 30s
cross (powerpc-unknown-linux-gnu)	1m 50s
test (macos, macos-latest, stable)	3m 52s
testbench	54s
cross (powerpc64-unknown-linux-gnu)	1m 40s
wasm32-unknown-emscripten	1m 53s
test (win-msvc, windows-latest, stable)	4m 47s
cross (s390x-unknown-linux-gnu)	2m 3s
wasm32-unknown-uknown	20s
wasm32-wasip1	1m 17s
win-gnu	2m 24s
	42m 33s

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