fix: remove redundant const qualifier on reference type

[rbqvq]

Description

CLANGARM64 emits -Wignored-reference-qualifiers
warning because 'const' on a reference type has no effect.

Removing it cleans up the build output and improves compatibility with LLVM toolchains.

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Unit tests have been added or updated for any new or modified functionality

AI Usage

• None: No AI tools were used in creating this PR
• Light: AI provided minor assistance (formatting, simple suggestions)
• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[rbqvq]

Original log here:

Warning: C:/a/Sunshine/Sunshine/third-party/libdisplaydevice/src/windows/settings_utils.cpp:45:77: warning: 'const' qualifier on reference type 'std::add_lvalue_reference_t<bool (const EnumeratedDevice &)>' (aka 'bool (&)(const EnumeratedDevice &)') has no effect [-Wignored-reference-qualifiers]
   45 |     std::set<std::string> getDeviceIds(const EnumeratedDeviceList &devices, const std::add_lvalue_reference_t<bool(const EnumeratedDevice &)> &predicate) {
      |  

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
404	2	402	3

View the top 2 failed test(s) by shortest run time

WinDisplayDeviceTopology::SetCurrentTopology_DuplicatedTopology

Stack Traces | 0.226s run time

D:.../unit/windows/test_win_display_device_topology.cpp:131
Value of: m_win_dd.setTopology(multiple_device_topology)
  Actual: false
Expected: true

WinDisplayDeviceTopology::SetCurrentTopology_MixedTopology

Stack Traces | 0.227s run time

D:.../unit/windows/test_win_display_device_topology.cpp:149
Value of: m_win_dd.setTopology(multiple_device_topology)
  Actual: false
Expected: true

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[ReenigneArcher]

Failing test is not a result of these changes. PR welcome if you have a fix for it.

[rbqvq]

Thanks, I think I don't have any fix plan :(