Remove specific number of jobs from comment

[radarhere]

Most of the Windows builds have started failing in the main branch - https://github.com/python-pillow/Pillow/actions/runs/3600683266

error C1047: The object or library file 'D:\a\Pillow\Pillow\winbuild\build\lib\lcms2_static.lib' was created by a different version of the compiler than other objects like 'build\temp.win32-3.7\Release\src_imagingcms.obj'; rebuild all objects and libraries with the same compiler

This has occurred previously in #5051. The solution was to change the cache key for the Windows build. This PR does that by updating a comment.

In #4701, a comment was added

Pillow/.github/workflows/test-windows.yml

Line 144 in 5bdf63e

# trim ~150MB x 9

There were 9 jobs at the time, but there are now more than that.