docs(install): keep old pyqt5 minimum version

Author: Alvaro-Kothe

doc/source/getting_started/install.rst

@@ -343,7 +343,7 @@ Installable with ``pip install "pandas[clipboard]"``.
 ======================================================================================================================================== ================== =============== ==============
 Dependency                                                                                                                               Minimum Version    pip extra       Notes
 ======================================================================================================================================== ================== =============== ==============
-`PyQt4 <https://pypi.org/project/PyQt4/>`__/`PyQt5 <https://pypi.org/project/PyQt5/>`__/ `PyQt6 <https://pypi.org/project/PyQt6/>`__     6.9.1              clipboard       Clipboard I/O
+`PyQt4 <https://pypi.org/project/PyQt4/>`__/`PyQt5 <https://pypi.org/project/PyQt5/>`__/ `PyQt6 <https://pypi.org/project/PyQt6/>`__     5.15.9             clipboard       Clipboard I/O
 `qtpy <https://github.com/spyder-ide/qtpy>`__                                                                                            2.3.0              clipboard       Clipboard I/O
 ======================================================================================================================================== ================== =============== ==============