Fix unsigned integer overflow in tapscript validation weight calculation

Author: MarcoFalke

src/script/script.h

@@ -51,10 +51,10 @@ static const uint32_t LOCKTIME_MAX = 0xFFFFFFFFU;
 static constexpr unsigned int ANNEX_TAG = 0x50;
 
 // Validation weight per passing signature (Tapscript only, see BIP 342).
-static constexpr uint64_t VALIDATION_WEIGHT_PER_SIGOP_PASSED = 50;
+static constexpr int64_t VALIDATION_WEIGHT_PER_SIGOP_PASSED{50};
 
 // How much weight budget is added to the witness size (Tapscript only, see BIP 342).
-static constexpr uint64_t VALIDATION_WEIGHT_OFFSET = 50;
+static constexpr int64_t VALIDATION_WEIGHT_OFFSET{50};
 
 template <typename T>
 std::vector<unsigned char> ToByteVector(const T& in)