Windows dependencies from GHA

[nulano]

After merging python-pillow/Pillow#4084, there are now several dependencies being fetched every time.

https://github.com/python-pillow/Pillow/runs/286114260#step:6:209:

Fetching https://github.com/ArtifexSoftware/ghostpdl-downloads/releases/download/gs927/ghostscript-9.27.tar.gz
Fetching https://iweb.dl.sourceforge.net/project/libjpeg-turbo/2.0.3/libjpeg-turbo-2.0.3.tar.gz
Fetching https://github.com/ImageOptim/libimagequant/archive/ba653c8ccb34dde4e21c6076d85a72d21ed9d971.zip
Fetching https://github.com/harfbuzz/harfbuzz/archive/2.6.1.zip
Fetching https://github.com/fribidi/fribidi/archive/v1.0.7.zip
Fetching https://github.com/HOST-Oman/libraqm/archive/v0.7.0.zip

There are also https://www.nasm.us/pub/nasm/releasebuilds/2.14.02/win64/nasm-2.14.02-win64.zip and https://bitbucket.org/pypy/pypy/downloads/pypy3.6-v7.2.0-win32.zip, but these are downloaded explicitly, so the workflow file would have to be updated to use these files from this repository.