Fixed models project mustache file

Author: Urganot

modules/openapi-generator/src/main/resources/aspnetcore/3.0/ModelsProject.csproj.mustache

@@ -38,7 +38,7 @@
     <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" {{^useCentralizedPackageVersionManagement}}Version="{{newtonsoftVersion}}" {{/useCentralizedPackageVersionManagement}}/>
 {{/useNewtonsoft}}
 {{/useSwashbuckle}}
-    <PackageReference Include="JsonSubTypes" {{^useCentralizedPackageVersionManagement}}Version="1.8.0" {{/useCentralizedPackageVersionManagement}}useCentralizedPackageVersionManagement}}/>
+    <PackageReference Include="JsonSubTypes" {{^useCentralizedPackageVersionManagement}}Version="1.8.0" {{/useCentralizedPackageVersionManagement}}/>
   </ItemGroup>
   <ItemGroup>
   </ItemGroup>