gnucash-on-windows master: Adapt build_package.ps1 to treat the 'unstable' branch like 'releases'.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash-on-windows/commit/86b08217 (commit)
	from  https://github.com/Gnucash/gnucash-on-windows/commit/24c6c02a (commit)



commit 86b082179ce66c65cc497577fd06ff9f06b6b834
Author: John Ralls <jralls at ceridwen.us>
Date:   Mon Apr 27 11:47:29 2020 -0700

    Adapt build_package.ps1 to treat the 'unstable' branch like 'releases'.



Summary of changes:
 buildserver/build_package.ps1 | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)