Fix duplicate keys in CODE_OPS dictionary

[JAGADISHSUNILPEDNEKAR]

Issue

The script.py file contained duplicate keys in the CODE_OPS dictionary:

• b"\xb1" had mappings to both "OP_NOP2" and "OP_CHECKLOCKTIMEVERIFY"
• b"\xb2" had mappings to both "OP_NOP3" and "OP_CHECKSEQUENCEVERIFY"

This is problematic because Python dictionaries only keep the last value for each duplicate key, which could lead to confusion and potential bugs.

Changes

• Removed the duplicate keys in the CODE_OPS dictionary
• Kept the more descriptive operation names (CHECKLOCKTIMEVERIFY and CHECKSEQUENCEVERIFY)
• Added comments to clarify that these opcodes are aliases

Testing

All tests pass with both unittest and pytest.