FEM on Colab changes

[angus-g]

From Firedrake Slack:

⚠️ Breaking change for FEM on Colab users ⚠️
...I have decided to do the following backward incompatible changes to FEM on Colab:

• users interested in firedrake development version should use the firedrake-install-development-real.sh installation script. (Note the -development- in the script name). The script installs PETSc from main, SLEPc from main and firedrake from master.
• users interested in firedrake latest release should use the firedrake-install-release-real.sh installation script. (Note the -release- in the script name). The script installs PETSc 3.22.*, SLEPc 3.22.*, (and in future firedrake from the latest released tag, while currently still uses the master branch while waiting for the first firedrake release). The version numbers 3.22 and (in future the firedrake tag) are hardcoded in the build script, and I will update them manually upon receiving news of new firedrake releases.
• the former installation script firedrake-install-real.sh (note, no -development- or -release-) is gone, and for the short term future will raise an error informing about the change.

See https://fem-on-colab.github.io/packages.html for updated instructions.
Considering the effort that is currently going on in firedrake versioned releases, when in doubt the suggestion would be to use the -release- installation URL.This message supersedes previous ones in the above thread.
I'd like to receive feedback on any issue, and whether you think this is a step in the right direction for your needs.