Update dotnet monorepo to 5.9.0

Author: renovate[bot]

src/OpenCvSharp.Analyzers/OpenCvSharp.Analyzers.csproj

@@ -22,8 +22,8 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.6.0" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="5.6.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.9.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="5.9.0" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>

test/OpenCvSharp.Analyzers.Tests/OpenCvSharp.Analyzers.Tests.csproj

@@ -14,7 +14,7 @@
     <PackageReference Include="xunit.runner.visualstudio" Version="4.0.0" PrivateAssets="all" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Analyzer.Testing" Version="1.1.4" />
     <!-- Override the old CodeAnalysis pulled in transitively by the testing framework -->
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.6.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.9.0" />
   </ItemGroup>
 
   <ItemGroup>