Fix off-by-one truncating SQL in fuzz target

_example/fuzz/fuzz_openexec.go

@@ -22,7 +22,7 @@ func FuzzOpenExec(data []byte) int {
 		return 0
 	}
 	defer db.Close()
-	_, err = db.Exec(string(data[:sep-1]))
+	_, err = db.Exec(string(data[:sep]))
 	if err != nil {
 		return 0
 	}