`ViolationCode` should be marked as non-exhaustive

[popematt]

ion-schema-rust/ion-schema/src/violation.rs

Lines 92 to 116 in 34eec9e

	/// Represents violation code that indicates the type of the violation
	#[derive(Debug, Clone, PartialEq, Eq)]
	pub enum ViolationCode {
	AllTypesNotMatched,
	AnnotationMismatched,
	ElementMismatched, // this is used for mismatched elements in containers
	ElementNotDistinct, // this is used for elements that are not distinct in containers
	FieldNamesMismatched, // this is used for mismatched field names in a struct
	FieldNamesNotDistinct, // this is used for field names that are not distinct in a struct
	FieldsNotMatched,
	InvalidIeee754Float, // this is used for ieee754_float constraint
	InvalidLength, // this is used for any length related constraints (e.g. container_length, byte_length, codepoint_length)
	InvalidNull, // if the value is a null for type references that doesn't allow null
	InvalidOpenContent, // if a container contains open content when `content: closed` is specified
	InvalidValue, // this is used for valid_values constraint
	MissingAnnotation, // if the annotation is missing for annotations constraint
	MissingValue, // if the ion value is missing for a particular constraint
	MoreThanOneTypeMatched,
	NoTypesMatched,
	RegexMismatched, // this is used for regex constraint
	TypeConstraintsUnsatisfied,
	TypeMatched,
	TypeMismatched,
	UnexpectedAnnotation, // if unexpected annotation is found for annotations constraint
	}

ViolationCode should be marked as #[non_exhaustive] so that new violation codes can be added if/when new versions of ISL add new constraints.