win build: use of debian unstable snapshots needs check-valid-until=no

see https://snapshot.debian.org/
>  To access snapshots of suites using Valid-Until that are older than a dozen days, it is necessary to ignore the Valid-Until header within Release files, in order to prevent apt from disregarding snapshot entries ("Release file expired"). Use aptitude -o Acquire::Check-Valid-Until=false update or apt-get -o Acquire::Check-Valid-Until=false update for this purpose.

(thanks to Axel Gembe for pointing this out)

contrib/build-wine/apt.sources.list

@@ -1,3 +1,3 @@
 deb https://snapshot.debian.org/archive/debian/20220811T031049Z/ bullseye main non-free contrib
 deb-src https://snapshot.debian.org/archive/debian/20220811T031049Z/ bullseye main non-free contrib
-deb https://snapshot.debian.org/archive/debian/20220811T031049Z/ sid main non-free contrib
+deb [check-valid-until=no] https://snapshot.debian.org/archive/debian/20220811T031049Z/ sid main non-free contrib

contrib/freeze_containers_distro.sh

@@ -39,7 +39,7 @@ echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_APPIMAGE_DISTRO} main non-free contrib
 echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main non-free contrib" >$contrib/build-wine/apt.sources.list
 echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main non-free contrib" >>$contrib/build-wine/apt.sources.list
 # we need win-iconv-mingw-w64-dev which is only in sid/unstable
-echo "deb ${DEBIAN_SNAPSHOT} unstable main non-free contrib" >>$contrib/build-wine/apt.sources.list
+echo "deb [check-valid-until=no] ${DEBIAN_SNAPSHOT} unstable main non-free contrib" >>$contrib/build-wine/apt.sources.list
 
 # android
 echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_ANDROID_DISTRO} main non-free contrib" >$contrib/android/apt.sources.list