do the nightly build against Coq master

1 job for master in 1 minute and 38 seconds
Status Job ID Name Coverage
failed #31984


Name Stage Failure
failed Build
[] no changes from git+
[] no changes from git+
[] synchronised from git+

The following dependencies couldn't be met:
- coq-iris -> coq >= dev -> ocaml >= 4.05.0
base of this switch (use `--unlock-base' to force)

ERROR: Job failed: exit code 1