Bump SteamKit2 from 2.4.0-Alpha.3 to 2.4.0

Bumps [SteamKit2](https://github.com/SteamRE/SteamKit) from 2.4.0-Alpha.3 to 2.4.0.
- [Release notes](https://github.com/SteamRE/SteamKit/releases)
- [Commits](https://github.com/SteamRE/SteamKit/compare/2.4.0-Alpha.3...2.4.0)

---
updated-dependencies:
- dependency-name: SteamKit2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

DepotDownloader/DepotDownloader.csproj

@@ -12,6 +12,6 @@
 
   <ItemGroup>
     <PackageReference Include="protobuf-net" Version="3.0.101" />
-    <PackageReference Include="SteamKit2" Version="2.4.0-Alpha.3" />
+    <PackageReference Include="SteamKit2" Version="2.4.0" />
   </ItemGroup>
 </Project>