Bump Avalonia.Diagnostics from 11.3.14 to 11.3.15

---
updated-dependencies:
- dependency-name: Avalonia.Diagnostics
  dependency-version: 11.3.15
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

ImageMerge/ImageMerge.csproj

@@ -15,7 +15,7 @@
         <PackageReference Include="Avalonia.Themes.Fluent" Version="12.0.1" />
         <PackageReference Include="Avalonia.Fonts.Inter" Version="12.0.1" />
         <!--Condition below is needed to remove Avalonia.Diagnostics package from build output in Release configuration.-->
-        <PackageReference Condition="'$(Configuration)' == 'Debug'" Include="Avalonia.Diagnostics" Version="11.3.14" />
+        <PackageReference Condition="'$(Configuration)' == 'Debug'" Include="Avalonia.Diagnostics" Version="11.3.15" />
         <PackageReference Include="Avalonia.ReactiveUI" Version="11.3.8"/>
         <PackageReference Include="MessageBox.Avalonia" Version="12.0.0"/>
         <PackageReference Include="NetVips" Version="3.2.0"/>