Update 1 NuGet dependencies

Author: github-actions[bot]

nanoFramework.SignalR.Client.nuspec

@@ -19,7 +19,7 @@
     <tags>nanoFramework C# csharp netmf netnf SignalR</tags>
     <dependencies>
       <dependency id="nanoFramework.CoreLibrary" version="1.12.0" />
-      <dependency id="nanoFramework.Json" version="2.2.8" />
+      <dependency id="nanoFramework.Json" version="2.2.15" />
       <dependency id="nanoFramework.System.Net.WebSockets.Client" version="1.1.6" />
     </dependencies>
   </metadata>

nanoFramework.SignalR.Client/nanoFramework.SignalR.Client.nfproj

@@ -47,8 +47,8 @@
       <HintPath>..\packages\nanoFramework.CoreLibrary.1.12.0\lib\mscorlib.dll</HintPath>
       <Private>True</Private>
     </Reference>
-    <Reference Include="nanoFramework.Json, Version=2.2.8.24404, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.Json.2.2.8\lib\nanoFramework.Json.dll</HintPath>
+    <Reference Include="nanoFramework.Json, Version=2.2.15.51152, Culture=neutral, PublicKeyToken=c07d481e9758c731">
+      <HintPath>..\packages\nanoFramework.Json.2.2.15\lib\nanoFramework.Json.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <Reference Include="nanoFramework.Runtime.Events, Version=1.10.0.3, Culture=neutral, PublicKeyToken=c07d481e9758c731">

nanoFramework.SignalR.Client/packages.config

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
   <package id="nanoFramework.CoreLibrary" version="1.12.0" targetFramework="netnanoframework10" />
-  <package id="nanoFramework.Json" version="2.2.8" targetFramework="netnanoframework10" />
+  <package id="nanoFramework.Json" version="2.2.15" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Runtime.Events" version="1.10.0" targetFramework="netnanoframework10" />
   <package id="nanoFramework.System.Collections" version="1.4.0" targetFramework="netnanoframework10" />
   <package id="nanoFramework.System.IO.Streams" version="1.1.9" />