CI macOS: swap version and arch position

was UltraGrid-<arch>-<version>.dmg (eg. UltraGrid-arm64-1.9.2.dmg),
which is not consistent with other platforms,
eg. UltraGrid-1.9.2-x86_64.AppImage and UltraGrid-1.9.2-win64.zip. The
one with the version just after UltraGrid seems to be more natural.

.github/scripts/environment.sh

@@ -20,7 +20,7 @@ fi
 
 # include platform on mac in version string
 if [ "$(uname -s)" = Darwin ]; then
-        VERSION="$(uname -m)-$VERSION"
+        VERSION="$VERSION-$(uname -m)"
 fi
 
 if [ -z "${CHANNEL-}" ]; then