Use native lineHeight on 26.0+ systems

[olejnjak]

When on iOS 26, watchOS 26 and tvOS 26 font(...) viewModifier uses newly added viewModifier lineHeight for setting line height instead of our computation.

Checklist

• Added tests (if applicable)

[Copilot]

Pull request overview

This PR adds support for using the native SwiftUI lineHeight view modifier on newer OS versions, but contains critical versioning errors. The PR references iOS 26.0, watchOS 26.0, and tvOS 26.0, which are non-existent versions. The correct versions should be iOS 18.0, watchOS 11.0, and tvOS 18.0 where the native lineHeight modifier was introduced.

Key changes:

• Adds conditional logic to use native lineHeight modifier on supposedly newer OS versions (though version numbers are incorrect)
• Updates CI/CD workflows to use macos-latest instead of macos-15
• Removes the .github/xcode-version file

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Sources/ACKategories/SwiftUIExtensions/FontModifier.swift	Adds availability check (with incorrect version numbers) and native lineHeight API usage for newer OS versions
CHANGELOG.md	Documents the feature addition with incorrect version reference
.github/xcode-version	Removes explicit Xcode version specification
.github/workflows/tests.yml	Updates runner from macos-15 to macos-latest
.github/workflows/docbuild.yml	Updates runner from macos-15 to macos-latest
.github/workflows/build.yml	Updates runner from macos-15 to macos-latest

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[olejnjak]

I am not entirely sure if we want such different behavior or not 😔

[komkovla]

I am for this change 👍 as this will be used system wide and actual difference between implementation is neglectable

[IgorRosocha]

LGTM, seem reasonable enough. 👍