Show $UPDATE_PKG_CACHE content in error message.

Fixes the typo in update_package_cache(), where the error message
 contained the color code twice, instead of the $UPDATE_PKG_CACHE text.

Signed-off-by: Jan Piskvor Martinec <github@piskvor.org>

automated install/basic-install.sh

@@ -1560,7 +1560,7 @@ update_package_cache() {
     else
         # show an error and exit
         printf "%b  %b %s\\n" "${OVER}" "${CROSS}" "${str}"
-        printf "  %bError: Unable to update package cache. Please try \"%s\"%b" "${COL_LIGHT_RED}" "${COL_LIGHT_RED}" "${COL_NC}"
+        printf "  %bError: Unable to update package cache. Please try \"%s\"%b" "${COL_LIGHT_RED}" "${UPDATE_PKG_CACHE}" "${COL_NC}"
         return 1
     fi
 }