3.1.0

Adds preliminary openapi v3.1.0 document processing

Over 50% of the 3.1.0 new json schema keyword features have been implemented
Preliminary 3.1.0 spec support includes these json schema keywords:

1. type (array of types supported in addition to one non-array value)
2. const: only string values are working because of bugs in swagger parser
3. contains
4. dependentRequired
5. dependentSchemas
6. maxContains
7. minContains
8. patternProperties
9. prefixItems
10. propertyNames
11. unevaluatedItems
12. unevaluatedProperties

What's Changed

• Adds 3.1.0 contains feature by @spacether in #205
• Adds 3.1.0 min/maxContains by @spacether in #208
• Adds 3.1.0 const feature by @spacether in #210
• Adds 3.1.0 dependentRequired by @spacether in #212
• Adds 3.1.0 dependent schemas by @spacether in #214
• Adds 3.1.0 json schema propertyNames by @spacether in #216
• Refactors schema class templates by @spacether in #217
• Adds patternProperties by @spacether in #220
• Adds prefixItems validation by @spacether in #222
• Adds unevaluatedItems schema feature by @spacether in #224
• Adds python 3.9 CI testing, fixes bug by @spacether in #227
• Adds unevaluatedProperties feature by @spacether in #229
• Bump actions/checkout from 3 to 4 by @dependabot in #235
• Adds 3.1.0 unit test spec by @spacether in #238
• Fixes documentation, adds validate invocation in schema examples by @spacether in #240
• Adds json schema test cases for 11 added keywords by @spacether in #241
• v3.1.0 release by @spacether in #245

Full Changelog: 3.0.0...3.1.0