Portablemc

Changes:
- *[Forge]* Fixed installation of forge with newer download API (87, thanks MTM828);
- *[Forge]* Deprecated `MINECRAFT_VERSION_NOT_FOUND` and added `MINECRAFT_VERSION_NOT_SUPPORTED` in `ForgeVersionNotFound` error;
- New class `OfflineAuthSession` that aims to replace the `username` and `uuid` fields in `StartOptions` class, these two fields are still supported but deprecated (83);
- The `DownloadEntry` class now allows providing fallbacks.

Changes:
- Fixed directories' creation with invalid version IDs (80)

Dev changes:
- Introduced a testy pipeline, will be improved in the future to avoid most regressions

Changes:
- The `--lwjgl` argument now supports the latest LWJGL version 3.3.1
- The `--lwjgl` no longer uses the "natives" section of libraries in the version metadata, it simply use the auto-extraction property of LWJGL, so for each OS, all types of natives are downloaded and LWJGL choose the right one.

Changes:
- Fixed the launcher core to the https://piston-meta.mojang.com endpoint for API
- Now using version manifest v2 in order to check metadata integrity with SHA1

Known issues:
- Internal version (show about) is showing 3.0.0

Changes:
- Workspace has been reworked, all modules resides in the `src/` directory, both add-ons and core module.
- Add-ons should now be installed from PIP, this has been a long-awaited feature, it's now easier to install add-ons.
- The launcher is no longer distributed as a single-script file.
- Dropped `modrinth` add-on in favor of ferium CLI.
- Improved `fabric`, `forge` and `archives` APIs to provide a non-CLI API in addition to a CLI addon.
- `DownloadList` now follows redirects.

Fixed:
- Added a fallback function for `datetime.datetime.fromisoformat(...)` for Python 3.6 (70).

Download and install:
To install PortableMC, please read this repository README, the single-file script is available below in the `portablemc-single` archive.