ci: rm unneeded apt upgrade

Now that 24.04 has been released, 'apt upgrade' is not needed anymore
for this job.

Author: knocte

.github/workflows/CI.yml

@@ -63,7 +63,6 @@ jobs:
       - name: Install dependencies
         run: |
           apt update --yes
-          apt upgrade --yes
 
           # NOTE: do not change the below with an `actions/setup-node` step! or it
           # would make this CI job entirely pointless