Bump LLamaSharp.Backend.Cpu from 0.19.0 to 0.26.0

Dependabot couldn't find the original pull request head commit, aec0b73.

Author: dependabot[bot]

desktop/PrivStack.Desktop/PrivStack.Desktop.csproj

@@ -93,7 +93,7 @@
     <PackageReference Include="NAudio" Version="2.2.1" />
     <!-- Local LLM Inference -->
     <PackageReference Include="LLamaSharp" Version="0.19.0" />
-    <PackageReference Include="LLamaSharp.Backend.Cpu" Version="0.19.0" />
+    <PackageReference Include="LLamaSharp.Backend.Cpu" Version="0.26.0" />
     <!-- Calendar ICS Import/Export -->
     <PackageReference Include="Ical.Net" Version="4.2.0" />
     <!-- LaTeX Math Rendering -->