add enum tag to jsonschema (sashabaranov#962)

* fix jsonschema tests

* ensure all run during PR Github Action

* add test for struct to schema

* add support for enum tag

* support nullable tag

Author: jtarchie

jsonschema/json.go

@@ -54,6 +54,7 @@ type Definition struct {
 	// Defs A map of reusable schema definitions.
 	Defs map[string]Definition `json:"$defs,omitempty"`
 	// MaxContains specifies the maximum number of elements in an array that can match the schema.
+	// MinContains specifies the minimum number of elements in an array that can match the schema.
 	MinContains int `json:"minContains,omitempty"`
 }