Update to latest lifetimes syntax

[natecook1000]

Moves from @lifetime to @_lifetime and the LifetimeDependence experimental feature to Lifetimes, eliminating a bunch of warnings in the latest compiler.

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary

[finagolfin]

I just tried to build the latest trunk from this repo on linux using the latest official Aug. 11 trunk 6.3 snapshot toolchain and saw a bunch of these lifetime errors:

/home/finagolfin/swift-binary-parsing/Sources/BinaryParsing/Parsers/Integer.swift:786:4: error: invalid lifetime dependence on an Escapable result
784 |
785 |   @inlinable
786 |   @_lifetime(&input)
    |    `- error: invalid lifetime dependence on an Escapable result                              
787 |   public init<T: SingleByteInteger>(                                                         
788 |     parsing input: inout ParserSpan,

I was confused, as you have a linux nightly CI, but I then found you are only testing 6.2, not the trunk 6.3 branch of the toolchain. Should we be avoiding 6.3 to build this repo?

[natecook1000]

Huh. I haven't tried the 6.3 snapshots yet, so can't say if there's a way to satisfy both given that error. This project targeting 6.2 right now, but I'll take a look at what 6.3 support requires 👍🏻