fixes sd3-version argument needed for mixed-bit compression

[c2p-cmd]

Adds fix for sd3-version in mixed_bit_compression_pre_analysis.py

Adds in the argument as it is needed in torch2coreml.py since, it is raises an error on line 1457.
The fix is straightforward

parser.add_argument(
        "--sd3-version",
        action="store_true",
        help=("If specified, the pre-trained model will be treated as an SD3 model."))

Thank you!