v0.7.7

ChainRules v0.7.7

Diff since v0.7.6

Closed issues:

• Should we run Zygote tests as part of CI? (#229)

Merged pull requests:

• Improvements to numeric exponent rules (#224) (@sethaxen)
• Fixup naming convention *_rrule -> *_pullback (#230) (@nickrobinson251)
• Add github action for Zygote CI (#231) (@sethaxen)