.windows-gitlab.yml: Fix windows build

For compiling libjpeg-turbo we need the Netwide Assembler (NASM). Unforunately the domain nasm.us which we are gathering it from is down. As we had problems in the past already, we now use one which is hosted on known location.

The zip was downloaded from https://github.com/ilammy/setup-nasm/blob/mirror/releasebuilds/2.15.05/win64/nasm-2.15.05-win64.zip.

We also use the x64 variant for both compilation architectures, as these don't have to match.