wxGUI/psmap: fix simple point graphic recalculate position

[tmszi]

Describe the bug
Changing the position of the simple point graphic prints an error message.

To Reproduce
Steps to reproduce the behavior:

1. Launch g.gui.psmap
2. Add one simple point graphic
3. Activate Pointer tool from the main toolbar
4. Try to interactively change simple point graphic position
5. See error

Traceback (most recent call last):
  File "/usr/lib64/grass84/gui/wxpython/psmap/frame.py", line 1605, in MouseActions
    self.OnLeftUp(event)
  File "/usr/lib64/grass84/gui/wxpython/psmap/frame.py", line 1849, in OnLeftUp
    self.RecalculatePosition(ids=[self.dragId])
  File "/usr/lib64/grass84/gui/wxpython/psmap/frame.py", line 2128, in RecalculatePosition
    rect.Offset(
TypeError: Rect.Offset(): arguments did not match any overloaded call:
  overload 1: argument 'dx' has unexpected type 'float'
  overload 2: 'dx' is not a valid keyword argument

Expected behavior
Changing the position of the simple point graphic should not prints an error message.

System description:

• Operating System: GNU/Linux
• GRASS GIS version: all

GRASS nc_basic_spm_grass7/PERMANENT:~ > python3 -c "import sys, wx; print(sys.version); print(wx.version())"
3.10.13 (main, Sep 16 2023, 22:24:59) [GCC 12.3.1 20230526]
4.2.0 gtk3 (phoenix) wxWidgets 3.2.2.1

Additional context
Rectangle widget with integer coordinates ,Offset() method dx,dy parameters require integer argument type.

Method doc:
https://docs.wxpython.org/wx.Rect.html#wx.Rect.Offset

[a-detiste]

In python3, the operator for integer division is //