chore: update osu-framework submodule to latest master (8097681bf) with optimizations and bug fixes

Updates include:
- Fix NullReferenceException in GraphicsPipeline.cs (ResourceLayouts?.Length)
- Fix null safety in VeldridExtensions.Clone() (ResourceLayouts null check)
- Fix null-forgiving operators in shader compilation (ShaderCompilationStore/VeldridShader)
- Performance optimizations: HashSet for hover tracking, LazyList struct enumerator
- Performance optimizations round 2: hot-path LINQ removal, array stats, single-pass trim
- Fix 30 CS1591 warnings from veldrid submodule + IL trimmer fixes
- Fix NuGet pack warnings for iOS project (NU5100, NU5118)
- Fix workflow failures: update action versions, fix shallow clone
- Remove redundant nullable operators per InspectCode warnings

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot