Add TODO for fuzz test

ConflictSet.cpp

@@ -1235,6 +1235,7 @@ int main(void) {
 
 #ifdef ENABLE_FUZZ
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  // TODO call setOldestVersion, and check range writes/reads
   initFuzz(data, size);
 
   int64_t writeVersion = 0;