feat: filter prerelease versions

[levibostian]

Filter pre-release versions unless dependency uses a pre-release version.

Like npm's semver module, pre-release versions should not be considered as versions to update unless the developer says so.

With this pull request, if this is the source code of the project:

import {foo} from "npm:ical-generator@1.0.0-develop.1"

...then udd would attempt to update to the latest version including the latest pre-release if there is one. This is the behavior of udd today.

If this is the source code of the project:

import {foo} from "npm:ical-generator@1.0.0"

... then udd would filter out all pre-release versions to update to and choose the latest one.

Closes: #80

[levibostian]

Doing some PR cleanup. Stale, so closing.