Bump MongoDB.Driver from 2.12.4 to 2.13.1

Bumps MongoDB.Driver from 2.12.4 to 2.13.1.

---
updated-dependencies:
- dependency-name: MongoDB.Driver
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

src/Akka.Persistence.MongoDb/Akka.Persistence.MongoDb.csproj

@@ -11,6 +11,6 @@
   <ItemGroup>
     <PackageReference Include="Akka.Persistence.Query" Version="$(AkkaVersion)" />
     <PackageReference Include="akka.streams" Version="$(AkkaVersion)" />
-    <PackageReference Include="MongoDB.Driver" Version="2.12.4" />
+    <PackageReference Include="MongoDB.Driver" Version="2.13.1" />
   </ItemGroup>
 </Project>