swc-windows-installer.py: Fix "it's hash" -> "its hash" typo
swc-windows-installer.py: Fix "it's hash" -> "its hash" typo

Reported-by: Steve Haddock <41c4a1d3df4cc2daf89fe10317b62e61e17a300f@mbari.org>

ethanwhite/windows-installer,swcarpentry/windows-installer,wking/swc-windows-installer