Support for Cairo 0.9

Summary

Adding support for Cairo 0.9.

What's Changed

• Preliminary audit report by @juniset in #40
• Use common.bool true and false by @pscott in #42
• Add return value to is_valid_signature by @pscott in #41
• Prevents Account reentrant signature reutilization by @juniset in #44
• Upgrade to Cairo v0.9.0 by @juniset in #45
• Audit report 16/05/2022 by @juniset in #46

New Contributors

• @pscott made their first contribution in #42

Full Changelog: v0.2.1...v0.2.2