fix: src/TestSite.14/TestSite.14.csproj to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DOTNET-MESSAGEPACK-8229907
- https://snyk.io/vuln/SNYK-DOTNET-UMBRACOCMSWEBCOMMON-8248482

src/TestSite.14/TestSite.14.csproj

@@ -7,7 +7,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="Umbraco.Cms" Version="14.2.0"/>
+        <PackageReference Include="Umbraco.Cms" Version="14.3.1"/>
         <PackageReference Include="uSync" Version="14.0.0"/>
     </ItemGroup>