scripts/setup: answering 'n' installed packages anyway

I ran `scripts/setup` to ensure my configuration was up to date. I answered 'n' to installing yosys, but the script went ahead and installed it anyway:

```
$ scripts/setup

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

libusb-1.0-0-dev/glinux-rodete-base-20211117.03.02,now 2:1.0.24-3 amd64 [installed]
Missing:
yosys
Missing packages: yosys
Install [y]/n? n
[sudo] password for avg:
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
berkeley-abc xdot
The following NEW packages will be installed:
berkeley-abc xdot yosys
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 7,678 kB of archives.
After this operation, 23.7 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
...
```