Update dependencies

Author: github-actions[bot]

nanoFramework.System.Collections.nuspec

@@ -20,7 +20,7 @@ This package requires a target with nanoFramework.System.Collections v$nativeVer
     <summary>nanoFramework.System.Collections assembly for nanoFramework C# projects</summary>
     <tags>nanoFramework C# csharp netmf netnf nanoFramework.System.Collections</tags>
     <dependencies>
-      <dependency id="nanoFramework.CoreLibrary" version="1.7.3" />
+      <dependency id="nanoFramework.CoreLibrary" version="1.8.0-preview.6" />
     </dependencies>
   </metadata>
   <files>

nanoFramework.System.Collections/nanoFramework.System.Collections.nfproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup Label="Globals">
     <NanoFrameworkProjectSystemPath>$(MSBuildToolsPath)..\..\..\nanoFramework\v1.0\</NanoFrameworkProjectSystemPath>
@@ -39,7 +39,7 @@
     </NFMDP_PE_ExcludeClassByName>
   </ItemGroup>
   <ItemGroup>
-    <NFMDP_PE_LoadHints Include="..\packages\nanoFramework.CoreLibrary.1.7.3\lib\mscorlib.dll">
+    <NFMDP_PE_LoadHints Include="..\packages\nanoFramework.CoreLibrary.1.8.0-preview.6\lib\mscorlib.dll">
       <InProject>false</InProject>
     </NFMDP_PE_LoadHints>
   </ItemGroup>
@@ -57,8 +57,8 @@
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>
-    <Reference Include="mscorlib, Version=1.7.3.5, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.CoreLibrary.1.7.3\lib\mscorlib.dll</HintPath>
+    <Reference Include="mscorlib, Version=1.8.0.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
+      <HintPath>..\packages\nanoFramework.CoreLibrary.1.8.0-preview.6\lib\mscorlib.dll</HintPath>
       <Private>True</Private>
     </Reference>
   </ItemGroup>

nanoFramework.System.Collections/packages.config

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="nanoFramework.CoreLibrary" version="1.7.3" targetFramework="netnanoframework10" />
+  <package id="nanoFramework.CoreLibrary" version="1.8.0-preview.6" targetFramework="netnanoframework10" />
   <package id="Nerdbank.GitVersioning" version="3.1.13-beta" developmentDependency="true" targetFramework="netnanoframework10" />
 </packages>