BUG #17934: Cannot run pgAdmin after upgrading from 15.2 to 15.3

The following bug has been logged on the website:

Bug reference:      17934
Logged by:          Tony Marston
Email address:      tony@tonymarston.net
PostgreSQL version: 15.3
Operating system:   Windows 10
Description:

I have just upgraded from version 15.2 to 15.3, but when I try to run
pgAdmin there is a long time delay before it comes up with the message: "The
pgAdmin 4 server could not be contacted". Below that it shows full details
of the error which ends with the following:

 import psutil
  File "E:\Program Files\PostgreSQL\15\pgAdmin
4\python\lib\site-packages\psutil\__init__.py", line 241, in <module>
    raise ImportError(msg)
ImportError: version conflict: 'E:\\Program Files\\PostgreSQL\\15\\pgAdmin
4\\python\\lib\\site-packages\\psutil\\_psutil_windows.cp310-win_amd64.pyd'
C extension module was built for another version of psutil (5.9.3 instead of
5.9.5); you may try to 'pip uninstall psutil', manually remove E:\Program
Files\PostgreSQL\15\pgAdmin
4\python\lib\site-packages\psutil\_psutil_windows.cp310-win_amd64.pyd or
clean the virtual env somehow, then reinstall

How do I fix this error?