fix some build issues

- use 'os.name' to decide between Windows/Linux build
- don't check Windows executable version number,
  since Wine fails to run the executable and causes release.sh to stop

scripts/release.sh

@@ -72,13 +72,6 @@ build-windows() {
         sleep 5
     done
     sleep 2
-
-    # check exe version
-    OUTPUT="$(wine gallery-dl.exe --version)"
-    if [[ ! "${OUTPUT%?}" == "${NEWVERSION}" ]]; then
-        echo "exe version mismatch: ${OUTPUT} != ${NEWVERSION}"
-        exit 3
-    fi
 }
 
 sign() {