Update 1 NuGet dependencies

Author: github-actions[bot]

nanoFramework.Graphics.nuspec

@@ -15,14 +15,15 @@
     <icon>images\nf-logo.png</icon>
     <repository type="git" url="https://github.com/nanoframework/nanoFramework.Graphics" commit="$commit$" />
     <copyright>Copyright (c) .NET Foundation and Contributors</copyright>
-    <description>This package includes the nanoFramework.Graphics assembly for .NET nanoFramework C# projects..&#10;This package requires a target with System.Math v$nativeVersion$ (checksum $checksum$).</description>
+    <description>This package includes the nanoFramework.Graphics assembly for .NET nanoFramework C# projects..
+This package requires a target with System.Math v$nativeVersion$ (checksum $checksum$).</description>
     <tags>nanoFramework C# csharp netmf netnf nanoFramework.Graphics</tags>
     <dependencies>
       <dependency id="nanoFramework.CoreLibrary" version="1.12.0-preview.9" />
       <dependency id="nanoFramework.ResourceManager" version="1.1.4-preview.8" />
       <dependency id="nanoFramework.Runtime.Events" version="1.10.0-preview.8" />
       <dependency id="nanoFramework.Runtime.Native" version="1.5.4-preview.5" />
-      <dependency id="nanoFramework.System.Collections" version="1.4.0-preview.16" />
+      <dependency id="nanoFramework.System.Collections" version="1.4.0-preview.21" />
     </dependencies>
   </metadata>
   <files>

nanoFramework.Graphics/nanoFramework.Graphics.nfproj

@@ -171,7 +171,7 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="nanoFramework.System.Collections, Version=1.4.0.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.System.Collections.1.4.0-preview.16\lib\nanoFramework.System.Collections.dll</HintPath>
+      <HintPath>..\packages\nanoFramework.System.Collections.1.4.0-preview.21\lib\nanoFramework.System.Collections.dll</HintPath>
       <Private>True</Private>
     </Reference>
   </ItemGroup>

nanoFramework.Graphics/packages.config

@@ -4,6 +4,6 @@
   <package id="nanoFramework.ResourceManager" version="1.1.4-preview.8" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Runtime.Events" version="1.10.0-preview.8" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Runtime.Native" version="1.5.4-preview.5" targetFramework="netnanoframework10" />
-  <package id="nanoFramework.System.Collections" version="1.4.0-preview.16" targetFramework="netnanoframework10" />
+  <package id="nanoFramework.System.Collections" version="1.4.0-preview.21" targetFramework="netnanoframework10" />
   <package id="Nerdbank.GitVersioning" version="3.3.37" developmentDependency="true" targetFramework="netnanoframework10" />
 </packages>