fix CI (WIP)

[robx]

No description provided.

[robx]

Log extract (for ghcup install ghc 8.0.2)

Info: Installing GHC (this may take a while)
Debug: Running sh with arguments ["./configure","--prefix=/usr/local/.ghcup/ghc/8.0.2"]
Debug: Running gmake with arguments ["DESTDIR=/usr/local/.ghcup/tmp/ghcup-60ce8deb918b9668","install"]
Error: [�]8;;[https://errors.haskell.org/messages/GHCup-00841�\GHCup-00841�]8;;�\]](https://errors.haskell.org/messages/GHCup-00841%1B/GHCup-00841%1B]8;;%1B/]) Process "gmake" with arguments ["DESTDIR=/usr/local/.ghcup/tmp/ghcup-60ce8deb918b9668",
                                "install"] failed with exit code 2.

[robx]

ghcup is up to date, and gmake is available:

$ which gmake
/usr/bin/gmake
$ gmake --version
GNU Make 4.3
Built for x86_64-pc-linux-gnu
Copyright (C) 1988-2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.