Unpin iota-crypto version

[olivereanderson]

Description of change

This PR specifies the iota-crypto dependencies used by this library to be in the range 0.7 up to (but NOT including) 0.10. #822 pinned the version to 0.9.1 which was necessary because 0.9.2 introduced a breaking change causing builds to fail. Now 0.9.2 has been yanked from crates.io and pinning is therefore no longer necessary.

Open questions

Before #822, we specified version ^0.7 for iota-crypto in our crates except for libjose (the reason 0.9.2 still got pulled was because of transitive dependencies (which pinning to 0.9.1 then prevented)), but as #822 demonstrated our library also worked with 0.9.1 and I have also tested with 0.8. Hence the question is do we use the range specified in this PR, or go back to ^0.7 or use ^0.9 which is now OK due to 0.9.2 being yanked?

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• Breaking change (fix or feature that would cause existing functionality to not work as expected)
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[cycraig]

Thanks, a version range is definitely the way this was meant to be done, rather than pinning.

Although we should probably stay with the latest version possible for security updates etc., I don't see any changes since 0.7.0 that should affect us, so the range is probably fine?