Fix doctests for Python 3.14

[cxzhong]

Fix all doctests exceptions raise changes in python 3.14.
1.Just for lazy_list, The from itertools import count is not picklable. It seems a new change in python 3.14.
2.In python 3.14, the error of PicklingError changes a lot. I have to use try.. except to detect it
Now fix #41028 with cython 3.1.5

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[cxzhong]

sage: from itertools import count
sage: from sage.misc.lazy_list import lazy_list
sage: m = lazy_list(count())
sage: x = loads(dumps(m))
/home/zhongcx/sage/local/var/lib/sage/venv-python3.14/lib/python3.14/site-packages/IPython/core/interactiveshell.py:3112: SyntaxWarning: 'return' in a 'finally' block
  return result
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
File sage/misc/persist.pyx:338, in sage.misc.persist.dumps()

AttributeError: type object 'sage.misc.lazy_list.lazy_list_from_iterator' has no attribute 'dumps'

During handling of the above exception, another exception occurred:

TypeError                                 Traceback (most recent call last)
Cell In[4], line 1
----> 1 x = loads(dumps(m))

File sage/misc/persist.pyx:340, in sage.misc.persist.dumps()

File sage/misc/persist.pyx:306, in sage.misc.persist._base_dumps()

File sage/misc/persist.pyx:830, in sage.misc.persist.SagePickler.dumps()

TypeError: cannot pickle 'itertools.count' object
when serializing tuple item 0
when serializing sage.misc.lazy_list.lazy_list_from_iterator reconstructor arguments
when serializing sage.misc.lazy_list.lazy_list_from_iterator object

Seems in python 3.14 we can not pickle itertools.count
I tested in python 3.13.7

>>> import pickle
>>> from itertools import count
>>> c = count(10, 2)
>>> pickle.dumps(c)
<python-input-3>:1: DeprecationWarning: Pickle, copy, and deepcopy support will be removed from itertools in Python 3.14.
b'\x80\x04\x95\x1f\x00\x00\x00\x00\x00\x00\x00\x8c\titertools\x94\x8c\x05count\x94\x93\x94K\nK\x02\x86\x94R\x94.'

in python 3.14

Python 3.14.0 (main, Oct 14 2025, 21:27:55) [Clang 20.1.4 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>  import pickle
  File "<python-input-0>", line 1
    import pickle
IndentationError: unexpected indent
>>> import pickle
>>> from itertools import count
>>> c = count(10, 2)
>>> pickle.dumps(c)
Traceback (most recent call last):
  File "<python-input-4>", line 1, in <module>
    pickle.dumps(c)
    ~~~~~~~~~~~~^^^
TypeError: cannot pickle 'itertools.count' object

So we have to change the doctest in lazy_list.
Relate to python/cpython#101588