Add constraint for pyqt5-sip on Python 3.8

setup.py

@@ -244,7 +244,7 @@ def run(self):
 
 # Qt bindings requirements
 qt_requirements = {
-    'pyqt5': ['pyqt5>=5.15,<5.16', 'pyqtwebengine>=5.15,<5.16'],
+    'pyqt5': ['pyqt5>=5.15,<5.16', 'pyqtwebengine>=5.15,<5.16', 'pyqt5-sip<12.16; python_version=="3.8"'],
     'pyqt6': ['pyqt6>=6.5,<7', 'pyqt6-webengine>=6.5,<7'],
 }
 

spyder/tests/test_dependencies_in_sync.py

@@ -237,6 +237,8 @@ def test_dependencies_for_spyder_setup_install_requires_in_sync():
     # We can't declare these as dependencies in setup.py
     for dep in ['python.app', 'fzf', 'fcitx-qt5']:
         full_reqs.pop(dep)
+    # Ignored `pyqt5-sip` constraint on conda
+    spyder_setup.pop('pyqt5-sip')
 
     assert spyder_setup == full_reqs