Fixed call to GenerationContextCreate for Postgres < 15

src/hnswbuild.c

@@ -492,7 +492,10 @@ InitBuildState(HnswBuildState * buildstate, Relation heap, Relation index, Index
 
 	buildstate->graphCtx = GenerationContextCreate(CurrentMemoryContext,
 											   "Hnsw build graph context",
-											   1024 * 1024, 1024 * 1024, 1024 * 1024);
+#if PG_VERSION_NUM >= 150000
+											   1024 * 1024, 1024 * 1024,
+#endif
+											   1024 * 1024);
 	buildstate->tmpCtx = AllocSetContextCreate(CurrentMemoryContext,
 											   "Hnsw build temporary context",
 											   ALLOCSET_DEFAULT_SIZES);