fix: swiftly is stuck during dependency check on Fedora

[terraputix]

Fix for #490.

The underlying issue was that using .discarded instead of .string(limit: 100 * 1024) will hang when waiting for user input. I verified this by running a bash script which waits for user input instead of yum list installed (from the changed line).
Since result.standardOutput is not currently being used the limit: 100 * 1024 could be smaller, but for simplicity I used the same value as in the apt-get version.

Moreover, yum list installed is not fully correct. Compare the following:

> yum list installed libuuid-devel
Updating and loading repositories:
Repositories loaded.
Available packages
libuuid-devel.i686   2.40.4-10.fc42 updates
libuuid-devel.x86_64 2.40.4-10.fc42 updates
> echo $?
0
> yum list --installed libuuid-devel
No matching packages to list
> echo $?
1

This shows that using --installed instead of installed will correctly return a non 0 exit code if a package is not installed.

[cmcgee1024]

Unfortunately, this may not be working with Amazon Linux 2, which doesn't have dnf options like --installed.

[terraputix]

What would your preferred solution for this look like? I guess it would be simplest to check the output of the command for a correctly installed package (similar to what is done for the apt-get version).
Alternatively, dnf could be called with yum as a fallback?