`mach try --worker-override` expects a worker-pool name, i.e.
`{provisioner}/{worker-type}`, not just `{worker-type}`.
For the special case of using dev scriptworkers, suggest `--worker-suffix` instead.
* fix warnings
* pin requirements to last known good
* removing release_workflows; removing sphinx-actdiag dep
- RTD builds are currently busted on funcparserlib, for some reason.
- Funcparserlib is pulled in from sphinx-actdiag.
- release_workflows/fx_ga_release is the only page that uses actdiag.
- release_workflows is a fairly old and out of date set of pages.
To solve the busted RTD builds, I'm removing sphinx-actdiag as a dep,
and the `release_workflows/` directory as well.
Julien Cristau
Aki Sasaki
Joel Maher