Apply suggestion from @asgerf

Co-authored-by: Asger F <asgerf@github.com>

Author: aschackmull

unified/ql/lib/codeql/unified/internal/ControlFlowGraph.qll

@@ -4,7 +4,7 @@
 overlay[local?]
 module;
 
-import unified
+private import unified
 private import codeql.controlflow.ControlFlowGraph
 private import codeql.controlflow.SuccessorType