chore(deps): Update dependency Google.Protobuf to 3.31.1 (#73)

This PR contains the following updates:

| Package | Change | Age | Confidence |
|---|---|---|---|
|
[Google.Protobuf](https://redirect.github.com/protocolbuffers/protobuf)
| `3.31.0` -> `3.31.1` |
[![age](https://developer.mend.io/api/mc/badges/age/nuget/Google.Protobuf/3.31.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/nuget/Google.Protobuf/3.31.0/3.31.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

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source/Dgraph/Dgraph.csproj

@@ -19,7 +19,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Google.Protobuf" Version="3.31.0" />
+    <PackageReference Include="Google.Protobuf" Version="3.31.1" />
     <PackageReference Include="Grpc.Core" Version="2.46.6" />
     <PackageReference Include="Grpc.Net.Client" Version="2.71.0" />
     <PackageReference Include="Grpc.Tools" Version="2.71.0" PrivateAssets="All" />