[C API] Remove token.h header file

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Symbols and functions exported by the <token.h> header file cannot be used outside Python internals. There is no public C API to tokenize a Python source file. I propose to simply remove this header file. It's not included by Python.h.

In Python 3.10, I removed the C API related to AST and the parser, since it was not possible to use it outside Python internals. See: https://docs.python.org/dev/whatsnew/3.10.html#id4

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Fixed by da5727a