Swagger-core 2.2.30 released!

• refs #4862 - resolve @notblank / @notempty as required (#4870)
• fix ArbitrarySchema (#4869)
• update Schema resolution and casting - add explicit-object-schema and use-arbitrary-schema sys/env props (#4868)
• refs #4859, refs #4860 - fix minLength and ModelResolver compatibility break (#4867)
• fix patternproperties handling in SpecFilter (#4818)