Fix deprecation warnings

[dafurman]

Context
I'm interested in using and contributing to this library a bit, but I saw there were a bunch of deprecation warnings. Most of them could be resolved with fix-its, and the few ones that didn't have fix-its weren't too bad. Figured I'd fix them to make the repo nicer to work in without all the ⚠️.

Testing
Existing tests pass

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files	Coverage Δ
...ces/SpyableMacro/Factories/CallsCountFactory.swift	100.00% <100.00%> (ø)
...ources/SpyableMacro/Factories/ClosureFactory.swift	100.00% <100.00%> (ø)
...acro/Factories/FunctionImplementationFactory.swift	100.00% <100.00%> (ø)
...ableMacro/Factories/ReceivedArgumentsFactory.swift	100.00% <100.00%> (ø)
...leMacro/Factories/ReceivedInvocationsFactory.swift	100.00% <100.00%> (ø)
...es/SpyableMacro/Factories/ReturnValueFactory.swift	100.00% <100.00%> (ø)
Sources/SpyableMacro/Factories/SpyFactory.swift	100.00% <100.00%> (ø)
...SpyableMacro/Factories/ThrowableErrorFactory.swift	100.00% <100.00%> (ø)
...SpyableMacro/Factories/VariablePrefixFactory.swift	100.00% <100.00%> (ø)
...cro/Factories/VariablesImplementationFactory.swift	98.61% <100.00%> (ø)

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[Matejkob]

Hey there,

Firstly, thank you for addressing the deprecation warnings. I'm well aware that the swift-syntax has been evolving rapidly, and with the advancements from WWDC to the official release of Swift 5.9, the API of the Swift syntax tree has undergone significant changes. This is likely the reason for the multitude of warnings we've been seeing. Your effort to not only notice but also rectify these warnings is commendable. Everything looks great on my end, and the fact that all existing tests pass speaks volumes about your meticulous approach.

I truly appreciate contributors like you who take the time to adapt to and improve upon the evolving codebase. Thanks again for your valuable contribution, and I'm eager to see more of your work in the future!

Thank you!