Bump protobuf-net from 3.2.52 to 3.2.56

---
updated-dependencies:
- dependency-name: protobuf-net
  dependency-version: 3.2.56
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

DepotDownloader/DepotDownloader.csproj

@@ -25,7 +25,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="protobuf-net" Version="3.2.52" />
+    <PackageReference Include="protobuf-net" Version="3.2.56" />
     <PackageReference Include="QRCoder" Version="1.7.0" />
     <PackageReference Include="SteamKit2" Version="3.3.0" />
   </ItemGroup>