fix: samples/server/petstore/fsharp-functions/OpenAPI/OpenAPI.fsproj to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-584431
- https://snyk.io/vuln/SNYK-DOTNET-NEWTONSOFTJSON-2774678
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-541850
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-610168
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-174572
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-173754
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-541849
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-72895
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-598231
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-174710
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-569073
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-1540881
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-3092931
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-174571
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-451559
- https://snyk.io/vuln/SNYK-DOTNET-MICROSOFTNETCOREAPP-1540883

Author: snyk-bot

samples/server/petstore/fsharp-functions/OpenAPI/OpenAPI.fsproj

@@ -8,7 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="1.0.24" />
-    <PackageReference Include="Newtonsoft.Json" Version="12.0.1" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
   </ItemGroup>
   <ItemGroup> 
     <None Include="host.json">