I tried to update Cmake to latest version $3\mathrm{.}31$ using pip get install cmake. It did show successfully but when i run the command to check the version it says $3\mathrm{.}18$ which is the old version. I had initally cleared the one with this command sudo apt$-$ get remove $--$purge cmake. I also tried to install it using using Kitware's APT repository but at the point of sudo apt get update. I get error: $403$ forbidden $($IP address here$)$

Failed to fetch $($ a link here$)$

Updating from such repository can't be done securely$...$

See apt$-$secure$(8)$ manpage for repository creation and user configuration.

I$\text{'}$m using ubuntu $18\mathrm{.}04,$ python $3\mathrm{.}6.$

My ethernet works okay and no firewall