CHANGELOG: write entry for 3.5.1

Like github.com/burrowers/garble, we now include links too.

cmd/shfmt: undo the Docker side of the version var rename

For mvdan#860, which is left open as a warning to users.

finalize changelog for v3.5.0

write changelog for v3.4.3

write changelog for v3.4.2

write changelog for v3.4.1

interp: start using pty.Start again

All we need to do is close the primary terminal after cmd.Wait.
This also ensures that file is kept alive for long enough,
preventing a GC run from closing the file before cmd.Wait.

After this change, I am still unable to reproduce a failure.

For more, see: creack/pty#127

finalize changelog for v3.4.0

add changelog entry for v3.3.1

interp: allow running Reset before Run

It can make sense, for example to make copies of a new runner to be used
later.

While at it, I noticed that Subshell failed to initialize the Vars map,
meaning that it wasn't filled at the end of Run.

Fixes mvdan#704.