Update to python-parser 0.3.0

[eed3si9n]

No description provided.

[eed3si9n]

error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
  --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rustpython-ast-0.3.0/src/impls.rs:60:1
   |
60 | static_assertions::assert_eq_size!(crate::Stmt, [u8; 160]);
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: source type: `generic::Stmt` (1216 bits)
   = note: target type: `[u8; 160]` (1280 bits)
   = note: this error originates in the macro `static_assertions::assert_eq_size` (in Nightly builds, run with -Z macro-backtrace for more info)

RustPython/Parser#114