Update to iOS 17 and new Spezi version

[Supereg]

Update to iOS 17 and new Spezi version

♻️ Current situation & Problem

This PR prepares SpeziStorage for the upcoming version of Spezi and replaces ObservableObject with Observable.

⚙️ Release Notes

• Update to iOS 17
• Compatibility with upcoming Spezi release
• Breaking: Replaces observable object with Observable.

📚 Documentation

Documentation was updated.

✅ Testing

Affected test code was updated.

📝 Code of Conduct & Contributing Guidelines

By submitting creating this pull request, you agree to follow our Code of Conduct and Contributing Guidelines:

• I agree to follow the Code of Conduct and Contributing Guidelines.

[PSchmiedmayer]

Nice, great job!

[codecov]

Codecov Report

Merging #16 (3ac67e4) into main (d3db2a6) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #16   +/-   ##
=======================================
  Coverage   91.65%   91.65%           
=======================================
  Files           6        6           
  Lines         431      431           
=======================================
  Hits          395      395           
  Misses         36       36           

Files	Coverage Δ
Sources/SpeziLocalStorage/LocalStorage.swift	89.43% <ø> (ø)
Sources/SpeziSecureStorage/SecureStorage.swift	93.34% <ø> (ø)

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[PSchmiedmayer]

Looks great!