Bump aws-smithy-http-server version (#4059)

When updating `aws-smithy-http-server (v0.63.4)` to depend on
`aws-smithy-json v0.61`, the minor version should have been bumped to
`0.64.0` instead of just increasing the patch version.

Current dependency tree:
```
aws-smithy-json v0.61.x
└── aws-smithy-http-server v0.63.4
```

This affects SDKs that have been generated by an older version of
`smithy-rs`:

```
aws-smithy-json v0.60.7
└── service-sdk v0.1.0 
aws-smithy-json v0.61.2
└── aws-smithy-http-server v0.63.4
    ├── service-sdk v0.1.0
```

This PR bumps `aws-smithy-http-server` to version `0.64.0`. It also
reverts the dependency changes that were part of [this
PR](https://github.com/smithy-lang/smithy-rs/pull/4014/files

).

Co-authored-by: Fahad Zubair <fahadzub@amazon.com>