Add `no_std` support #80

Job	Run time
Minimal Versions Native MSRV	1m 25s
Build & Test Chrome	1m 3s
Minimal Versions Native MSRV (all features)	1m 25s
Build & Test Chrome (all features)	1m 17s
Minimal Versions Web MSRV	1m 38s
Build & Test Chrome with Atomics	1m 18s
Minimal Versions Web MSRV (all features)	1m 37s
Build & Test Chrome with Atomics (all features)	1m 18s
Minimal Versions Native	15s
Build & Test Firefox	1m 6s
Minimal Versions Native (all features)	13s
Build & Test Firefox (all features)	1m 12s
Build & Test Firefox with Atomics	1m 11s
Minimal Versions Web	32s
Build & Test Firefox with Atomics (all features)	1m 7s
Minimal Versions Web (all features)	23s
Build & Test Safari	1m 35s
Build & Test Safari (all features)	1m 23s
Build & Test Safari with Atomics	1m 18s
Build & Test Safari with Atomics (all features)	1m 21s
Build Web MSRV	1m 39s
Build Native MSRV	1m 16s
Build & Test Native	22s
	25m 54s

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