Use python decimal classes within the JSON parser to prevent floating…

…-point errors causing a validation failure.

Observed in testnet e.g. 2023-10-07 below

INFO:root:***RESULTS***
Height of proof: 2530608
Block proven against: 000000000000009ebfcdeb127badf0e55bc7c3656e13acf85ccf792fbecef1a3
Claimed amount (sats): 21029955090998
Proven amount(sats): 21029955090997
INFO:root:IMPORTANT! Call this script with --reconsider to bring your bitcoin node back to tip when satisfied with the results
WARNING: More claimed 21029955090998 than proven 21029955090997

validate_reserves.py

@@ -3,6 +3,7 @@
 import argparse
 import copy
 from collections import Counter
+import decimal
 import json
 import logging
 import math
@@ -37,7 +38,7 @@ def wrapper(method, params=[], **kwargs):
             r = requests.post(self.bitcoind, json=data, **kwargs)
             logging.debug(r.text)
             r.raise_for_status()
-            result = r.json()
+            result = r.json(parse_float=decimal.Decimal)
             if result["error"] is not None:
                 raise JsonRPCException(result["error"])
             return result["result"]