This is "Edit" and not "Open With" which is a file association?

(Easiest way for
file associations is a re-install using the
customise option which has a section for associations.)
For Edit: Open the registry editor (regedit.exe) and navigate to the following key:
[HKEY_CLASSES_ROOT\SystemFileAssociations\image\shell\edit\command]
and change the default Windows editor to point to the Gimp executable.
"C:\Program Files\GIMP 2\bin\gimp-2.10.exe" "%1" Note the quotes because of the spaces in the file name.

Of course, these values can be exported as backups, so attached is a zip file.
Unpack it. Three small files
gimpedit.reg for a regular gimp 2.10,
partha2-10-8.reg for the latest Partha regular version &
restore.reg to set back to the Win editor.
Click on the one you want, accept the dire warnings that Windows throws out, and that is all.