Feat/automate release

[mmolari]

Added the tools/release.sh script. Usage example: bash tools/release.sh 0.6.1.

This script will:

• check that the user is on the master branch.
• check that there are no uncommitted changes.
• check that the desired version is not already present in the repo.
• check that the version argument matches the expected pattern "X.Y.Z" .
• check that the version matches the version reported in Project.toml
• check that CHANGELOG.md has an entry for the release version, and use it to generate release notes.

If these conditions are met, the script will generate a release draft, to be inspected and approved on github.

I also updated the releasing.md file in the documentation