Pin libxml2 version to 2.13.7

[antonwolfy]

This PR pins libxml2 version to 2.13.7 due to libs dependency issue with 2.14.0 version as reported on #146.

Without that change the conda package can not be build through GitHub action, since conda-build raises error:

Traceback (most recent call last):
  File "C:\Users\runneradmin\miniconda3\envs\build\Scripts\conda-build-script.py", line 6, in <module>
    from conda_build.cli.main_build import execute
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\site-packages\conda_build\cli\main_build.py", line 19, in <module>
    from .. import api, build, source, utils
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\site-packages\conda_build\api.py", line [24](https://github.com/IntelPython/dpnp/actions/runs/14267019048/job/39991206345#step:8:25), in <module>
    from .config import DEFAULT_PREFIX_LENGTH as _prefix_length
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\site-packages\conda_build\config.py", line 28, in <module>
    from .utils import (
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\site-packages\conda_build\utils.py", line 51, in <module>
    import libarchive
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\site-packages\libarchive\__init__.py", line 1, in <module>
    from .entry import ArchiveEntry
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\site-packages\libarchive\entry.py", line 6, in <module>
    from . import ffi
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\site-packages\libarchive\ffi.py", line [26](https://github.com/IntelPython/dpnp/actions/runs/14267019048/job/39991206345#step:8:27), in <module>
    libarchive = ctypes.cdll.LoadLibrary(libarchive_path)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\ctypes\__init__.py", line 460, in LoadLibrary
    return self._dlltype(name)
           ^^^^^^^^^^^^^^^^^^^
  File "C:\Users\runneradmin\miniconda3\envs\build\Lib\ctypes\__init__.py", line 379, in __init__
    self._handle = _dlopen(self._name, mode)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: [WinError 1[27](https://github.com/IntelPython/dpnp/actions/runs/14267019048/job/39991206345#step:8:28)] The specified procedure could not be found

Here is a link to the full log with the error.

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• Have you added documentation for your changes, if necessary?
• Have you added your changes to the changelog?

[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/index.html

[coveralls]

coverage: 72.271%. remained the same
when pulling 8f765c8 on build-issue-on-win
into 41a7059 on master.

[github-actions]

Array API standard conformance tests for dpnp=0.18.0dev0=py312he4f9c94_69 ran successfully.
Passed: 1197
Failed: 0
Skipped: 14