Persist repo ref hashes in db

database/db.go

@@ -159,6 +159,16 @@ CREATE TABLE runners (
     name    TEXT,
     secret  TEXT
 );
+
+CREATE TABLE pipeline_refs (
+	name			TEXT PRIMARY KEY NOT NULL,
+	pipeline_id 	UUID NOT NULL,
+	hash			TEXT NOT NULL,
+
+    CONSTRAINT fk_pipeline_id
+        FOREIGN KEY(pipeline_id)
+            REFERENCES pipelines(id)
+);
 `
 
 	_, err := conn.Exec(context.Background(), createTablesQuery)