Hello everyone i wanted to install python,dkms,sudo and pip3 but i cant see the pictures, i added followin line in the /etc/apt/source.list
saved it and wanted to update but then it shows following error:

and this error comes when i use

I hope anyone can help me.
Code:
deb http://download.proxmox.com/debian/pve buster pve-no-subscription

and this error comes when i use
Code:
apt -y install python3 python3-pip git build-essential pve-headers dkms jq

I hope anyone can help me.