Swift 6 support

[IMCHO]

It seems that the project has concurrency problems with swift-tools-version 6.0.

[brnnmrls]

Curious if this related to #263 ? I'd need some more information in order to confirm.

[IMCHO]

@brnnmrls That could be related. Have you set the tool version 6.0 at the time?

[brnnmrls]

Apologies for the delay, but yes I did.

[IMCHO]

Thanks. I'll try it and make a pr.