st_tree: add versions 1.4.0 and 1.3.0

[safi-huss]

Summary

Changes to recipe: st_tree[1.4.0/1.3.0]

Motivation

Have the latest versions of the library

Details

1.3.0 -> 1.4.0 breadth method introduced
1.2.2 -> 1.3.0 Minor fixes

---

• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• If this is a bug fix, please link related issue or provide bug details
• Tested locally with at least one configuration using a recent version of Conan

[safi-huss]

This is my first submission, so let me be transparent on what I did.
I downloaded the release packages from the authors Github archive:

curl -sL -o st_tree_1.3.0.tar.gz "https://github.com/erikerlandson/st_tree/archive/refs/tags/version_1.3.0.tar.gz"
curl -sL -o st_tree_1.4.0.tar.gz "https://github.com/erikerlandson/st_tree/archive/refs/tags/version_1.4.0.tar.gz"

And then ran the checksum

sha256sum st_tree_1.3.0.tar.gz st_tree_1.4.0.tar.gz

The URLs and these checksums were added to recipes/st_tree/all/conandata.yml

[ErniGH]

Thanks for your PR 😄. Please add only the latest version of the library.

[safi-huss]

Thanks for your PR 😄. Please add only the latest version of the library.

Done with the new commit.