Removes dashing support.

[francocipollone]

Part of #249

[agalbachicar]

LGTM

[agalbachicar]

BTW, aren't you removing the docker images for bionic?

[francocipollone]

BTW, aren't you removing the docker images for bionic?

Forgot to comment about it, thanks for asking.
I haven't removed the dockerfiles for bionic but I modified the scripts to use focal by default.

Even though we are removing support to 18, I felt that there is no harm about having the script allowing you to set up a 18.04 container if needed. However, for consistency I think I should remove it and avoid having to maintain this in the future. Wdyt? I guess you're inclined to remove it, right?

[agalbachicar]

Git tracks everything :) No harm in removing it.
We could document in the docs the last commit with dashing support though.

[francocipollone]

We could document in the docs the last commit with dashing support though.

Interesting to extend it for all the repos not only maliput_infra. Adding in maliput_documentation a note with the hashes of all the repos with official dashing support?

[agalbachicar]

Right.

[agalbachicar]

Actually, that's what tags are for :)

[francocipollone]

Actually, that's what tags are for :)

To continue here: #254

[francocipollone]

CI passing. maliput/delphyne#842 Is fixing delphyne test.

[agalbachicar]

LGTM