3.0.0 : Require Node >= 18 and drop callback support

Breaking changes

Requires Node >= 18
Callback style is no longer supported natively. You can migrate your code by wrapping any functions with a Bluebird Promise and then calling .nodeify (basically reverse what was done in #111 and #116) or using some other nodeify library that converts Promises into callbacks. However, please note that using the Bluebird library itself recommends using native Promises instead.
The loadFromFile function is no longer available, as this method let you pass a file name dynamically which in some cases can be hijacked. To replace it, you can load the file yourself and pass that to the loadFromString method instead.
Functions now return native Promises instead of Bluebird Promises; these should behave normally if you are already using Bluebird Promises as if they were regular Promises, i.e. if you're just using natively supported functions such as .then(). However any Bluebird-specific functions will not be available (i.e. .reflect(), isFulfilled()), so if you are using these you will need to either wrap the Promise with a Bluebird Promise, or preferably convert your code to use the native Promise implementation instead.

Schema.org microdata now supports self closing tags and respects content attribute.

Change dead link in test by @mvolz in #107
Remove support for node <18 by @mvolz in #108
Replace preq with fetch in tests by @mvolz in #109
[BREAKING CHANGE] Remove preq from library by @mvolz in #110
[BREAKING CHANGE] Remove support for callback (node-style) requests by @mvolz in #111
Update eslint-config-wikimedia and lint by @mvolz in #112
[BREAKING CHANGE] Use native Promises by @mvolz in #116
Add blank line by @mvolz in #113
Update linting library by @mvolz in #114
build: Bump mocha from 10.3.0 to 11.1.0 by @jdforrester in #117
build: update microdata-node and add tests by @mvolz in #118
Update README.md by @mvolz in #119

Full Changelog: v2.0.1...v3.0.0