cubestore-router unable to resolve s3 address in govcloud

**Describe the bug**
Hi, I'm trying to run cubestore-router in a govcloud region (us-gov-west-1) and am hitting the following error:

```
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: CubeError { message: "AWS S3 error: error sending request for url (https://$redacted/?prefix=cubejs%2Fcubestore%2Fmetastore-current&list-type=2): error trying to connect: dns error: failed to lookup address information: Name or service not known", backtrace: "", cause: Internal }', /build/cubestore/cubestore/src/config/mod.rs:1935:34
stack backtrace:
rust_begin_unwind
/rustc/dc80ca78b6ec2b6bba02560470347433bcd0bb3c/library/std/src/panicking.rs:584:5
core::panicking::panic_fmt
/rustc/dc80ca78b6ec2b6bba02560470347433bcd0bb3c/library/core/src/panicking.rs:142:14
core::result::unwrap_failed
/rustc/dc80ca78b6ec2b6bba02560470347433bcd0bb3c/library/core/src/result.rs:1805:5
as core::future::future::Future>::poll
as core::future::future::Future>::poll
as core::future::future::Future>::poll
as core::future::future::Future>::poll
as core::future::future::Future>::poll
as core::future::future::Future>::poll
cubestored::main::{{closure}}
std::thread::local::LocalKey::with
tokio::park::thread::CachedParkThread::block_on
tokio::runtime::thread_pool::ThreadPool::block_on
tokio::runtime::Runtime::block_on
cubestored::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
```

govcloud uses a different s3 endpoint, which you can configure in rust-s3, see [here](https://docs.rs/rust-s3/latest/s3/enum.Region.html). I would be perfectly fine with defining that endpoint myself via an environment variable, or to get the rust-s3 package updated with govcloud regions.

govcloud s3 endpoints: https://docs.aws.amazon.com/govcloud-us/latest/UserGuide/govcloud-s3.html

**To Reproduce**
Steps to reproduce the behavior:
Run cubestore-router using s3 in a govcloud region

**Expected behavior**
cubestore-router should be able to conenct to s3

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Version:**
0.34.20

**Additional context**
Add any other context about the problem here.