Update pre-commit configuration (backport #28)

[mergify]

Changes Made

This PR adds the following changes:

1. Updates the .pre-commit-config.yaml file to include gersemi for CMakeLists.txt formatting
2. Sets main to ROS 2 Rolling
3. Fixes old syntax issue in Dockerfile

This will currently break the Gazebo installation, but allows me to backport to Jazzy and get set up for Humble and Iron.

---

This is an automatic backport of pull request #28 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of d48bcbd has failed:

On branch mergify/bp/humble/pr-28
Your branch is up to date with 'origin/humble'.

You are currently cherry-picking commit d48bcbd.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   .devcontainer/nouveau/devcontainer.json
	modified:   .devcontainer/nvidia/devcontainer.json
	modified:   example_pkg/CMakeLists.txt

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .devcontainer/nouveau/Dockerfile
	both modified:   .devcontainer/nvidia/Dockerfile
	both modified:   .docker/Dockerfile
	both modified:   .github/workflows/ci.yml
	both modified:   .github/workflows/docker.yml
	both modified:   .pre-commit-config.yaml
	both modified:   .vscode/c_cpp_properties.json
	both modified:   .vscode/settings.json

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally