DepotDownloader: Update protobuf-net dependency.

DepotDownloader/DepotDownloader.csproj

@@ -58,8 +58,9 @@
     <PlatformTarget>AnyCPU</PlatformTarget>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="protobuf-net, Version=2.0.0.612, Culture=neutral, PublicKeyToken=257b51d87d2e4d67, processorArchitecture=MSIL">
-      <HintPath>..\packages\protobuf-net.2.0.0.612\lib\net40\protobuf-net.dll</HintPath>
+    <Reference Include="protobuf-net, Version=2.0.0.621, Culture=neutral, PublicKeyToken=257b51d87d2e4d67, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\packages\protobuf-net.2.0.0.621\lib\net40\protobuf-net.dll</HintPath>
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core">
@@ -104,6 +105,7 @@
   </ItemGroup>
   <ItemGroup>
     <None Include="app.config" />
+    <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\..\SteamKit2\SteamKit2\SteamKit2.csproj">

DepotDownloader/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="protobuf-net" version="2.0.0.621" targetFramework="net40" />
+</packages>