github will cease support using username/password for login

Github will stop supporting username/password for accessing:

Basic authentication using a password to Git is deprecated and will soon no longer work. 

Visit https://github.blog/2020-12-15-token-authentication-requirements-for-git-operations/ for more

 information around suggested workarounds and removal dates.

Beginning August 13, 2021, we will no longer accept account passwords when authenticating Git operations

 on GitHub.com. For developers, if you are using a password to authenticate Git operations with GitHub.com

 today, you must begin using a personal access token over HTTPS (recommended) or SSH key by August 13, 

2021, to avoid disruption.

I'm not very familiar with how the token can be used. I assume that is for HTTPS. As I know, for daily pull/

push, SSH key is commonly used. You can follow instruction to generate the RSA key pair, and upload the

public key to Github.  If run into issue, refer to troubleshoot common SSH Problems, especially

Reviewing your SSH keys

If run 'ssh-add -l -E sha256' gives 'The agent has no identities', probably you haven't run ssh-add to add the

 key to ssh-agent. You can run: ssh-add -E sha256, then rerun with '-l'. 

For your exist local repository, may need update the remote url as this:

Check remote url: git remote -v

Update remote url: git remote set-url origin git@github.com:your_github_username/your_proj.git
Note, it is 'git@' but not 'your_username@'.