Bump Confluent.Kafka to 2.8.0 (#428)

Author: Arkatufus

src/Directory.Packages.props

@@ -11,7 +11,7 @@
   <!-- App dependencies -->
   <ItemGroup>
     <PackageVersion Include="Akka.Streams" Version="$(AkkaVersion)" />
-    <PackageVersion Include="Confluent.Kafka" Version="2.2.0" />
+    <PackageVersion Include="Confluent.Kafka" Version="2.8.0" />
     <PackageVersion Include="Testcontainers.Kafka" Version="4.1.0" />
   </ItemGroup>