Add `no_std` support #68

Job	Run time
Minimal Versions Native MSRV	15s
Build & Test Chrome	1m 16s
Minimal Versions Native MSRV (all features)	15s
Build & Test Chrome (all features)	1m 36s
Minimal Versions Web MSRV	19s
Build & Test Chrome with Atomics	1m 28s
Minimal Versions Web MSRV (all features)	17s
Build & Test Chrome with Atomics (all features)	1m 30s
Minimal Versions Native	10s
Build & Test Firefox	1m 9s
Minimal Versions Native (all features)	12s
Build & Test Firefox (all features)	1m 33s
Minimal Versions Web	11s
Build & Test Firefox with Atomics	1m 14s
Minimal Versions Web (all features)	11s
Build & Test Firefox with Atomics (all features)	1m 8s
Build & Test Safari	1m 16s
Build & Test Safari (all features)	1m 21s
Build & Test Safari with Atomics	1m 50s
Build & Test Safari with Atomics (all features)	1m 22s
Build Web MSRV	2m 13s
Build Native MSRV	2m 5s
Build & Test Native	23s
	23m 14s

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