[test] Update mock server for Swift 6 compliance #450

Job	Run time
Semantic Version label check	4s
musl	1m 26s
Unit tests / Construct unit test matrix	5s
Integration Tests / No dependencies on Foundation	2m 1s
Integration Tests / Test archive plugin	2m 23s
Integration Tests / Test Examples/APIGateway on 6.0.1-amazonlinux2	1m 19s
Integration Tests / Test Examples/APIGateway+LambdaAuthorizer on 6.0.1-amazonlinux2	1m 23s
Soundness / API breakage check	1m 41s
Integration Tests / Test Examples/BackgroundTasks on 6.0.1-amazonlinux2	1m 18s
Soundness / Documentation check	1m 25s
Integration Tests / Test Examples/HelloJSON on 6.0.1-amazonlinux2	1m 14s
Integration Tests / Test Examples/HelloWorld on 6.0.1-amazonlinux2	1m 9s
Soundness / License headers check	4s
Integration Tests / Test Examples/S3_AWSSDK on 6.0.1-amazonlinux2	4m 13s
Soundness / Unacceptable language check	5s
Integration Tests / Test Examples/S3_Soto on 6.0.1-amazonlinux2	4m 48s
Integration Tests / Test Examples/Streaming on 6.0.1-amazonlinux2	1m 16s
Soundness / Format check	41s
Soundness / Broken symlinks check	3s
Integration Tests / Test Examples/Testing on 6.0.1-amazonlinux2	1m 22s
Integration Tests / Test Examples/Tutorial on 6.0.1-amazonlinux2	1m 14s
Soundness / Python lint check	5s
Soundness / Shell check	33s
Soundness / YAML lint check	5s
Swift 6 Language Mode / Swift 6 language mode	1m 14s
Unit tests / Unit tests / Linux (6.0)	1m 18s
Unit tests / Unit tests / Linux (nightly-6.0)	1m 35s
Unit tests / Unit tests / Linux (nightly-main)	1m 32s
	35m 36s

Provide feedback