Upgrade Smithy (#1330)

* Upgrade to Smithy 1.16.2

* Remove extra test fixed in Smithy 1.16.2

* Upgrade to Smithy 1.16.3

* Remove extra test fixed in Smithy 1.16.3

* Remove failing expectation from server tests

* Upgrade to Smithy 1.17.0

* Upgrade to Smithy 1.18.1

* Upgrade to Smithy 1.19.0

* Upgrade to Smithy 1.21.0

* Update changelog

* Fix Gradle repositories