fix(brain_qt): fix signal has no connect member

`pylint` detects `Qt` signals as `FunctionDef`s instead of
`ClassDef`s, so they are not properly detected in PySide2 5.15.2+ and
PySide6. The patch from PR #900 is used to fix this.

Fixes PyCQA/pylint #4040 and PyCQA/pylint #5378

Author: adamgranthendry

astroid/brain/brain_qt.py

@@ -71,6 +71,17 @@ def emit(self, signal): pass
     )
 
 
+def _looks_like_pyside2_or_6_signal(node):
+    """Detect a PySide2 or PySide6 signal.  These changed locations as of QT 5ish apparently."""
+
+    is_pyside_node = node.qname().partition(".")[0] in {"PySide2", "PySide6"}
+    is_named_signal = any(
+        cls.qname() == "Signal" for cls in node.instance_attrs.get("__class__", [])
+    )
+
+    return is_pyside_node and is_named_signal
+
+
 register_module_extender(AstroidManager(), "PyQt4.QtCore", pyqt4_qtcore_transform)
 AstroidManager().register_transform(
     nodes.FunctionDef, transform_pyqt_signal, _looks_like_signal
@@ -80,3 +91,6 @@ def emit(self, signal): pass
     transform_pyside_signal,
     lambda node: node.qname() in {"PySide.QtCore.Signal", "PySide2.QtCore.Signal"},
 )
+AstroidManager().register_transform(
+    nodes.FunctionDef, transform_pyqt_signal, _looks_like_pyside2_or_6_signal
+)