v0.18.1

What's Changed

• new test for closing trades after maturity by @dpaiton in #196
• add calculate_approximate_short_bonds_given_base_deposit by @dpaiton in #198
• add calculate_short_bonds_given_deposit by @dpaiton in #199
• Bump versions by @ryangoree in #201

Full Changelog: v0.18.0...v0.18.1