text: Title: Error in Renaming the Node
  Body: <!-- In the following, please describe your issue in detail! -->
  <!-- If some of the sections do not apply, just remove them. -->
  
  ### Short description
  Error while Renaming node created using FlowChart class
  
  ### Code to reproduce
  <!-- Please provide a minimal working example that reproduces the issue in the code block below.
       Ideally, this should be a full example someone else could run without additional setup. -->
  ```python
  from PyQt5 import QtWidgets as Qtw
  from pyqtgraph.flowchart import Flowchart
  
  
  class MainWindow(Qtw.QWidget):
      def __init__(self, *args, **kwargs):
          super().__init__(*args, **kwargs)
          layout = Qtw.QGridLayout()
  
          # Create flowchart, define input/output terminals
          fc = Flowchart(terminals={
              'Input': {'io': 'in'},
              'Output': {'io': 'out'},
          })
  
          layout.addWidget(fc.widget())
          self.setLayout(layout)
          self.show()
  
  
  if __name__ == '__main__':
      import sys
      app = Qtw.QApplication(sys.argv)
      w = MainWindow(windowTitle="create FlowChart")
      sys.exit(app.exec_())
  ```
  
  ### Expected behavior
  No Traceback
  
  ### Real behavior
  <!-- What happens? -->
  
  ```
  Traceback (most recent call last):
    File "T:\flowchart_test\env\lib\site-packages\pyqtgraph\flowchart\Flowchart.py", line 219, in nodeRenamed
      self.sigChartChanged.emit(self, 'rename', node)
    File "T:\flowchart_test\env\lib\site-packages\pyqtgraph\flowchart\Flowchart.py", line 701, in nodeRenamed
  
  KeyError: <Node lol @25bd816a7a0>
  
  ```
  
  ### Tested environment(s)
  
   * PyQtGraph version: 0.12.3
   * Qt Python binding:  PyQt5
   * Python version:  3.10
   * Operating system: Windows 10
   * Installation method: pip
  