From 2021-08-13, GitHub is no longer accepting account passwords when authenticating Git operations. You need to add a PAT (Personal Access Token) instead, and you can follow the below method to add a PAT on your system.

Create Personal Access Token on GitHub

From your GitHub account, go to Settings → Developer Settings → Personal Access Token → Tokens (classic) → Generate New Token (Give your password) → Fillup the form → click Generate token → Copy the generated Token, it will be something like ghp_sFhFssdfdfgfhtLjmks4Tzuzgthdvfsrta

on My Ubuntu:

For Linux, you need to configure the local GIT client with a username and email address,

$ git config --global user.name "your_github_username"
$ git config --global user.email "your_github_email"
$ git config -l

Once GIT is configured, we can begin using it to access GitHub. Example:

$ git clone https://github.com/YOUR-USERNAME/YOUR-REPOSITORY
> Cloning into `YOUR-REPOSITORY`...
Username: <type your username>
Password: <type your password or personal access token (GitHub)

Now cache the given record in your computer to remembers the token:

$ git config --global credential.helper cache

If needed, anytime you can delete the cache record by:

$ git config --global --unset credential.helper
$ git config --system --unset credential.helper

Now try to pull with -v to verify

$ git pull -v