v1.17.0

ChainRulesCore v1.17.0

Diff since v1.16.0

Merged pull requests:

• Stop testing on 1.5 (#616) (@mcabbott)
• Fix typos in documentation (#621) (@lostella)
• Change link to SemVer ref (#627) (@DanielVandH)
• Add explanation of nothing errors (#633) (@gdalle)
• Define getproperty on AbstractZeroTangents (#636) (@oxinabox)

Closed issues:

• (to be deleted) (#631)