Remove Dgraph support from the codebase.

Dgraph-related functionality, configuration, and benchmarks have been removed from the project. This streamlines the codebase to focus on supported backends, specifically eliminating Dgraph references in favor of Neo4j and other implementations. Version bumped to reflect the changes.

pkg/database/factory.go

@@ -31,7 +31,7 @@ type DatabaseConfig struct {
 }
 
 // NewDatabase creates a database instance based on the specified type.
-// Supported types: "badger", "dgraph", "neo4j"
+// Supported types: "badger", "neo4j"
 func NewDatabase(
 	ctx context.Context,
 	cancel context.CancelFunc,