refactor: Updated 'upgrade requirements' workflow to use reusable workflows

[edx-requirements-bot]

Additional information from script execution

Python code cleanup by the cleanup-python-code Jenkins job.

This pull request was generated by the cleanup-python-code Jenkins job, which ran

cd .github/workflows;  TEAM_REVIEWERS=$(grep 'team-reviewers=' upgrade-python-requirements.yml -m 1 | awk '{print $2}'); TEAM_REVIEWERS=${TEAM_REVIEWERS/--team-reviewers=/}; SCHEDULE=$(grep 'cron:' upgrade-python-requirements.yml -m 1 | sed 's/^.*: //');   EMAIL_TO=$(grep 'to:' upgrade-python-requirements.yml -m 1 | sed 's/^.*: //'); [ -z $(grep 'Send success notification' upgrade-python-requirements.yml) ] && SEND_SUCCESS_NOTIFICATION=$(echo false) || SEND_SUCCESS_NOTIFICATION=$(echo true); : > upgrade-python-requirements.yml; printf "name: Upgrade Requirements\n\non:\n  schedule:\n     - cron: ${SCHEDULE}\n  workflow_dispatch:\n     inputs:\n       branch:\n         description: 'Target branch to create requirements PR against'\n         required: true\n         default: \$default-branch\njobs:\n   call-upgrade-python-requirements-workflow:\n    with:\n       branch: \${{ github.event.inputs.branch }}\n       team_reviewers: ${TEAM_REVIEWERS}\n       email_address: ${EMAIL_TO}\n       send_success_notification: ${SEND_SUCCESS_NOTIFICATION}\n    secrets:\n       requirements_bot_github_token: \${{ secrets.REQUIREMENTS_BOT_GITHUB_TOKEN }}\n       requirements_bot_github_email: \${{ secrets.REQUIREMENTS_BOT_GITHUB_EMAIL }}\n       edx_smtp_username: \${{ secrets.EDX_SMTP_USERNAME }}\n       edx_smtp_password: \${{ secrets.EDX_SMTP_PASSWORD }}\n    uses: edx/.github/.github/workflows/upgrade-python-requirements.yml@master\n" >> upgrade-python-requirements.yml;

The following packages were installed:
``

[matthugs]

@Jawayria this will not work. $default-branch is a template feature, not syntax which gets interpolated in general workflow files.

from https://github.com/edx/super-csv/runs/4373685050?check_suite_focus=true

[Jawayria]

@matthugs Thanks so much for pointing it out. I tested this workflow in some repos before running cleanup job in bulk but this issue didn't come up as we set branch name to 'master' here if input is empty and most of the repos had 'master' as default branch.
I've started propagating this correction in other repos as well.