Update swiftformat

[jpgrayson]

This updates the validation tooling to use swiftformat 0.52.10 (was 0.48.17).

I'm assuming there is value in updating tooling from time to time. If not, we can just close this PR.

This updated version of swiftformat does drive several formatting changes. The most common is to change, e.g.:

if let thing = thing {
    ...
}

to

if let thing {
    ...

which seems like a nice enough improvement.

[adam-fowler]

Is if let thing available in swift 5.7? I thought it came in 5.9.
MQTTNIO supports the last three minor releases of Swift which include 5.7

[jpgrayson]

Since swiftformat is configured for a particular minimum swift version, I was sort of trusting it to do the right thing in this regard.

The CI build/test with swift 5.7 also works.

So it seems like this is okay.

[adam-fowler]

Of course you're right. Thanks for all the changes.

[jpgrayson]

Thank you for taking the time to review these PR's. I very much appreciate your help!

[adam-fowler]

All your changes are in v2.11.0