gh-153903: Fix ctypes wrap_dll_function() with string annotations

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Call get_annotations() with eval_str=True.

• Issue: Annotation-based decorator for ctypes function pointers #153903

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@ctypes.util.struct has the same bug: see PR gh-154040 which fixes it.

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cc @ZeroIntensity

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With this change, the following example:

import ctypes.util

@ctypes.util.wrap_dll_function(ctypes.pythonapi)
def Py_GetVersion() -> 'invalid return type':
    ...

now fails with SyntaxError:

Traceback (most recent call last):
  File "/home/vstinner/python/main/ann.py", line 3, in <module>
    @ctypes.util.wrap_dll_function(ctypes.pythonapi)
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/home/vstinner/python/main/Lib/ctypes/util.py", line 582, in decorator
    annotations = annotationlib.get_annotations(func, eval_str=True)
  File "/home/vstinner/python/main/Lib/annotationlib.py", line 1078, in get_annotations
    else eval(_rewrite_star_unpack(value), globals, locals)
         ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 1
    invalid return type
            ^^^^^^
SyntaxError: invalid syntax

Hopefully, the traceback starts at line 3 of ann.py which is the line creating Py_GetVersion(), so the traceback is correct and helpful!

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Merged, thanks for the review.