Update 1 NuGet dependencies

Author: github-actions[bot]

nanoFramework.Networking.Sntp.nuspec

@@ -19,7 +19,7 @@
 This package requires a target with nanoFramework.Networking.Sntp v$nativeVersion$ (checksum $checksum$).</description>
     <tags>nanoFramework C# csharp netmf netnf nanoFramework.Networking.Sntp sntp</tags>
     <dependencies>
-      <dependency id="nanoFramework.CoreLibrary" version="1.12.0-preview.18" />
+      <dependency id="nanoFramework.CoreLibrary" version="1.12.0-preview.19" />
     </dependencies>
   </metadata>
   <files>

nanoFramework.Networking.Sntp/nanoFramework.Networking.Sntp.nfproj

@@ -49,7 +49,7 @@
   </ItemGroup>
   <ItemGroup>
     <Reference Include="mscorlib, Version=1.12.0.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.CoreLibrary.1.12.0-preview.18\lib\mscorlib.dll</HintPath>
+      <HintPath>..\packages\nanoFramework.CoreLibrary.1.12.0-preview.19\lib\mscorlib.dll</HintPath>
       <Private>True</Private>
     </Reference>
   </ItemGroup>

nanoFramework.Networking.Sntp/packages.config

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="nanoFramework.CoreLibrary" version="1.12.0-preview.18" targetFramework="netnanoframework10" />
+  <package id="nanoFramework.CoreLibrary" version="1.12.0-preview.19" targetFramework="netnanoframework10" />
   <package id="Nerdbank.GitVersioning" version="3.3.37" developmentDependency="true" targetFramework="netnanoframework10" />
 </packages>