v5.21.0

• feat: Data Package v2, support exclusiveMinimum, exclusiveMaximum properties (#1840)
• feat: Data Package v2, relax constraints on name property
• doc: new page "Advanced Topics" > "Data Package version" that details how frictionless-py handles different versions of datapackage.
• fix: missing $schema property is properly interpreted as datapackage version 1 ; with custom $schema profile, the validation is lenient and handles a superset of v1 and v2 features (#1857)