[action] [PR:12959] Pin requests to version 2.31.0 in main.yml

[mssonicbld]

Description of PR

Summary: Fixes # (issue)

Type of change

• [ ] Bug fix
• [ ] Testbed and Framework(new/improvement)
• [ ] Test case(new/improvement)

Back port request

• [ ] 201911
• [ ] 202012
• [ ] 202205
• [ ] 202305
• [ ] 202311

Approach

What is the motivation for this PR?

In latest requests python package, would got error in some steps like add-topo and restart-ptf with message 'Not supported URL scheme http+docker' We already have fix PR https://github.com/sonic-net/sonic-mgmt/pull/12910 in master branch to install stable requests version in docker.yml, but once package_installation was set to false like restart-ptf, docker.yml would skip and report error again

How did you do it?

Install stable requests version in main.yml after executing docker.yml to cover all scenario

How did you verify/test it?

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[mssonicbld]

Original PR: https://github.com/sonic-net/sonic-mgmt/pull/12959