Also updates fabric loader.

The [old page](https://fabricmc.net/versions.html) is missing links to the online javadocs. It tells users to use the [new page](https://fabricmc.net/develop) instead, so we might as well provide the new one here to begin with.

Using JAVA_17 is currently broken with the production server and not necessarily indicated by how Mixin treats this field

* Update yarn and fabric load/api

To keep up to date with https://fabricmc.net/versions.html?&version=1.17.1

* Set loader to latest stable version

This commit can be used as an example on how to update your mod to Java 16. You will need to ensure you have Java 16 installed and set as the active version to run this.

Gradle 7 is required along with loom 0.8