Update 1 NuGet dependencies

Author: github-actions[bot]

Tests/UnitTestsSerialPort/UnitTestsSerialPort.nfproj

@@ -51,7 +51,7 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="nanoFramework.System.Text, Version=1.1.3.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\..\packages\nanoFramework.System.Text.1.1.3-preview.4\lib\nanoFramework.System.Text.dll</HintPath>
+      <HintPath>..\..\packages\nanoFramework.System.Text.1.1.3-preview.7\lib\nanoFramework.System.Text.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <Reference Include="nanoFramework.TestFramework, Version=1.0.172.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">

Tests/UnitTestsSerialPort/packages.config

@@ -3,6 +3,6 @@
   <package id="nanoFramework.CoreLibrary" version="1.12.0-preview.1" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Hardware.Esp32" version="1.3.5-preview.5" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Runtime.Events" version="1.10.0-preview.4" targetFramework="netnanoframework10" />
-  <package id="nanoFramework.System.Text" version="1.1.3-preview.4" targetFramework="netnanoframework10" />
+  <package id="nanoFramework.System.Text" version="1.1.3-preview.7" targetFramework="netnanoframework10" />
   <package id="nanoFramework.TestFramework" version="1.0.172" targetFramework="netnanoframework10" developmentDependency="true" />
 </packages>