Add shellcheck to CI

[penberg]

The shellcheck too is great at catching bugs in shell scripts so let's add it to the CI.

[tjyang]

Out of curiosity, I managed to install shellcheck and scan install-deps.sh on Fedora 37.

1st time encounter haskell app ;-| , Hope others can pick this up.

[me@t430 sqld]$ shellcheck  scripts/install-deps.sh ;date;which shellcheck

In scripts/install-deps.sh line 8:
    . /etc/os-release
      ^-------------^ SC1091 (info): Not following: /etc/os-release was not specified as input (see shellcheck -x).

For more information:
  https://www.shellcheck.net/wiki/SC1091 -- Not following: /etc/os-release wa...
Sat Feb 25 09:00:47 PM CST 2023
/home/me/.cabal/bin/shellcheck
[me@t430 sqld]$