Update for more recent Julia versions

[rdeits]

• Require Julia 1.6 (the current LTS) as the minimum Julia version
• Require Rotations.jl 1.1 and rename UnitQuaternion -> QuatRotation to match
• Update all Manifest.toml files to the new format and re-generate them on the latest Julia release
• Test Julia 1.6 and the latest release on CI

[ferrolho]

Hi Robin! Thanks for taking the time to do this.

FYI, I have an open MR for the rotations: #629. It looks very similar to your changes, except perhaps for

quat = convert(QuatRotation{T}, rot)
w, x, y, z = Rotations.params(quat)

which I remember having to do at that time to retrieve w, x, y, z; but maybe now we can get it without doing Rotations.params(quat).

On a related note, I've created a new release on my personal fork just yesterday: ferrolho/RigidBodyDynamics.jl@v2.4.0. Maybe it can serve as inspiration for what the next release of the Julia Robotics repo could be. I'm happy to help taking this through!

[rdeits]

Ah, nice, I prefer your params solution over directly accessing the fields. I've cherry-picked your commits into this PR. Thanks for the updated release--once we have all the tests and CI working here we can create another one with the fast version of Rotations.jl.

[ferrolho]

Remaining CI error can be fixed with #636

[ferrolho]

We could increment it to 2.4.0 instead.

[rdeits]

fixed, thanks

[ferrolho]

Good to merge from my end (I don't have permissions to do it).