fix: src/TestSite.10/TestSite.10.csproj to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DOTNET-SIXLABORSIMAGESHARP-7547406
- https://snyk.io/vuln/SNYK-DOTNET-MESSAGEPACK-8229907
- https://snyk.io/vuln/SNYK-DOTNET-SIXLABORSIMAGESHARP-6615678
- https://snyk.io/vuln/SNYK-DOTNET-SIXLABORSIMAGESHARP-6615679
- https://snyk.io/vuln/SNYK-DOTNET-SIXLABORSIMAGESHARP-7547407

src/TestSite.10/TestSite.10.csproj

@@ -7,7 +7,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="Umbraco.Cms" Version="10.8.6"/>
+        <PackageReference Include="Umbraco.Cms" Version="10.8.7"/>
         <PackageReference Include="uSync" Version="10.7.3"/>
     </ItemGroup>