Hardcode string in miniupnpcstring.h and remove wine requirement from deps-win32.yml

Credit: sipa, cfields, Luke-Jr and michagogo contributed to this fix.

Removing wine as a win32 build dep is beneficial to fixing Gitian LXC,
which would enable many more people to join in the gitian.sigs process
by being able to build with a linux VM instead of a virt capable host.
Merge pull request #3042 from wtogami/nowinedep

Hardcode string in miniupnpcstring.h and remove wine from deps-win32.yml