Update InfluxDBClient.Point to be Sendable

[CraigSiemens]

Proposal:
Update InfluxDBClient.Point to conform to the Sendable protocol.

In theory it should be a simple change, though it's possible there's other concurrency warning that would be surfaced by adding the change.

It'd be really nice if InfluxDBClient.Point was a struct. That'd simplify adding the sendable conformance since an instance of a struct can't be referenced for multiple threads, removing the need for adding synchronization/locking which a class would require.

Current behavior:
When using the library with Swift 6, the following error is produced when passing a point across concurrent contexts.

Desired behavior:
An error shouldn't be produced.

Use case:
Using the package with Swift 6.

[bednar]

Hi @CraigSiemens,

thanks for your suggestion.

Is this something you would be willing to help with? All PR is welcome and we will be happy to review your submission.

Best Regards