v1.6.1

What's Changed

• Bump requirements by @mpharrigan in #854
• Reformat src/openfermion using black formatter. by @fdmalone in #846
• Fix pytest deprecation warnings. by @fdmalone in #852
• Fix scipy sqrtm precision issue by @fdmalone in #864
• Remove limit on cirq by @fdmalone in #867

Full Changelog: v1.6.0...v1.6.1