Add requirements.txt

[IamPhytan]

Thank you for creating this package ! It helps a lot for building simple dashboards for teleop missions.

For easy debugging on new systems, I often install the minimal dependencies and run ./run. Yet, it's a little annoying when we need to check the package.xml or the README.md files to get the list of dependencies. So, I added a requirements.txt for faster installation.

[dheera]

Thanks!