packages depending on conf-time fail on the CI

[Jason Gross]

https://gitlab.com/coq/opam-coq-archive/-/jobs/336910827

[ERROR] The compilation of conf-time failed at "/usr/bin/which time".

#=== ERROR while compiling conf-time.1 ========================================#
# context              2.0.5 | linux/x86_64 | ocaml-base-compiler.4.05.0 | https://opam.ocaml.org#be531661
# path                 ~/opam-root-4.05.0-2.0.5-plain/4.05.0/.opam-switch/build/conf-time.1
# command              /usr/bin/which time
# exit-code            1
# env-file             ~/opam-root-4.05.0-2.0.5-plain/log/conf-time-20988-af3201.env
# output-file          ~/opam-root-4.05.0-2.0.5-plain/log/conf-time-20988-af3201.out

[Enrico Tassi]

Try adding time here: https://github.com/coq/opam-coq-archive/blob/master/.gitlab-ci.yml#L20