feature request: Add bump build number bot command

[matthewfeickert]

It would be useful to add a conda-forge-webservices command that is along the lines of

@conda-forge-admin, please bump build number

that would increase the build number by 1. This would be helpful for PRs by non-maintainers that are opened up via the conda-forge-admin, please rerender command (conda-forge/r-juicyjuice-feedstock#3) that do rerender the feedstock, but then as the command issuer isn't a feedstock maintainer they can't push to the conda-forge-admin's branch to update the build number along with the rerender.

Example: conda-forge/r-juicyjuice-feedstock#4

This is similar to, but not the same as Issue #250.

[matthewfeickert]

I'm confirming that from the conda-forge Zulip chat

#general > ✔ Unable to download latest version of py-wake @ 💬

it is noted that

Anyone can open a PR (or ask the bot to open one, though then a maintainer has to do the build number bump)