ci: test with Python 3.14

[vlaci]

No description provided.

[vlaci]

There is a cstruct related error:

Traceback (most recent call last):
  File "/home/runner/work/unblob/unblob/.venv/bin/jefferson", line 4, in <module>
    from jefferson.cli import main
  File "/home/runner/work/unblob/unblob/.venv/lib/python3.14/site-packages/jefferson/cli.py", line 7, in <module>
    from jefferson.jffs2 import extract_jffs2
  File "/home/runner/work/unblob/unblob/.venv/lib/python3.14/site-packages/jefferson/jffs2.py", line 11, in <module>
    import cstruct
  File "/home/runner/work/unblob/unblob/.venv/lib/python3.14/site-packages/cstruct/__init__.py", line 32, in <module>
    from .abstract import AbstractCEnum, AbstractCStruct, CStructMeta
  File "/home/runner/work/unblob/unblob/.venv/lib/python3.14/site-packages/cstruct/abstract.py", line 34, in <module>
    from .c_parser import Tokens, parse_enum, parse_enum_def, parse_struct, parse_struct_def
  File "/home/runner/work/unblob/unblob/.venv/lib/python3.14/site-packages/cstruct/c_parser.py", line 40, in <module>
    from .c_expr import c_eval
  File "/home/runner/work/unblob/unblob/.venv/lib/python3.14/site-packages/cstruct/c_expr.py", line 170, in <module>
    ast.Num: lambda node: node.n,
    ^^^^^^^
AttributeError: module 'ast' has no attribute 'Num'

[qkaiser]

jefferson lock is now set to use cstruct version 6.1 - onekey-sec/jefferson#36

[qkaiser]

According to pypi cstruct is not yet compatible with Python 3.14. Might be the right opportunity to move from cstruct to dissect.cstruct in jefferson 🐍