CI tests failing due to missing Mongo DB

[jaraco]

It seems that since the last time I was working on this project, the GHA environments have evolved not to have MongoDB installed by default. As a result, the tests are failing.

I looked into using something like this action, but it simultaneously does too much and too little. In particular, it allows configuration of a single MongoDB instance in a separate container. It doesn't allow for the types of integrations demanded by jaraco.mongodb, which itself facilitates the creation of MongoDB servers in different configurations (standalone and replica sets). Moreover, it doesn't work on Windows or Mac at all.

I've started work in feature/install-mongodb to facilitate the download and installation of MongoDB on various platforms.

[jaraco]

Fixed in #33