windows release fix

not sure how could this work before, but we need to copy version.txt to
huggle_core before initiating build since that's where it's going to
look for it

with this change it seems to be possible to build the release package
even under much newer VS 2017, although we need to target even newer VS
2022 in the future (there is no support for Qt5, only Qt6 from that one
onwards though)

windows/release.ps1

@@ -154,6 +154,9 @@ if ($git_enabled -and (Test-Path("..\.git")))
 {
     echo "build: non-git build (windows)" > version.txt
 }
+
+cp version.txt huggle_core\
+
 if (!(Test-Path("huggle_core\definitions.hpp")))
 {
     cp "huggle_core\definitions_prod.hpp" "huggle_core\definitions.hpp"