experiment: do nightly build against Coq master

1 job for master in 15 minutes and 55 seconds
Status Job ID Name Coverage
  Build
failed #31541
fp
build-iris.dev

00:15:55

 
Name Stage Failure
failed
build-iris.dev Build
Makefile.coq:320: recipe for target 'all' failed
make[1]: *** [all] Error 2
Makefile:6: recipe for target 'all' failed
make: *** [all] Error 2

real 0m12.374s
user 0m16.056s
sys 0m1.708s
ERROR: Job failed: exit code 1