gentoo has started raising an error in the docker-images repository - https://github.com/python-pillow/docker-images/actions/runs/18206199669/job/51837059727#step:6:2183

300.9 sudo: PAM account management error: Authentication service cannot retrieve authentication info
300.9 sudo: a password is required

This is happening when using sudo inside depends/install_libavif.sh or depends/install_raqm.sh. Testing, I've found that if we stop using sudo, the script succeeds.

This PR suggests not forcing users to use sudo, by removing the command from those scripts.