feat: add a scheduled release cut workflow to cut release branches

[mihir20]

Description

Purpose

Automates biweekly release branch creation for rudder-server.

Two repository variables control the behavior:

• PAUSE_AUTO_RELEASE — set to "true" to skip scheduled releases (release freeze). Manual workflow_dispatch still works so you can override the freeze if needed.
• RELEASE_WEEK_PARITY — set to "even" (default) or "odd" to control which ISO weeks are release weeks.

Trigger

• Cron: Every Monday at 8:30 AM UTC (2:00 PM IST)
• Manual: workflow_dispatch with optional version override

Jobs

1. check-schedule

• Enforces biweekly cadence using ISO week number (even week = release week)
• Manual dispatches always proceed

2. release-cut

Runs only if check-schedule says it's a release week.

Notable Details

• Requires contents: write permission for pushing branches
• Uses pinned actions/checkout (SHA for v4.3.0)
• Slack notification uses slackapi/slack-github-action@v1.26.0

Linear Ticket

Security

• The code changed/added as part of this pull request won't create any security issues with how the software is being used.

[atzoum]

Do we really need to schedule this? Can't we just trigger it manually?

[mihir20]

manual trigger is also there if we need to trigger release manually

[atzoum]

I don't think we need the automatic trigger, but will let @ktgowtham decide :)

[ktgowtham]

We generally get confirmation from team members of any pending PRs before cutting a release. So with scheduled action, we might sometimes need to cut it again, if team members aren't ready.
I'm fine keeping it manual for now.
But thanks for this PR, we don't need to do these steps manually now. Also avoids any typo issues when creating branches.

[mihir20]

I think keeping this automated will make people get their PRs merged before the cut. We can try to keep this automated for sometime, if we feel that automation is not required, we can disable the schedule.

wdyt?

[ktgowtham]

okay. let's communicate to wider team about this and that their PRs need to be merged before the scheduled time. anything later, they'll have to reach out to consider the PR.
Let's add a slack reminder in #server-dev a day before to merge any pending PRs before the cut off time.

[mihir20]

also I am adding two repository variables to control the behavior:

• PAUSE_AUTO_RELEASE — set to "true" to skip scheduled releases (release freeze). Manual workflow_dispatch still works so you can override the freeze if needed.
• RELEASE_WEEK_PARITY — set to "even" (default) or "odd" to control which ISO weeks are release weeks.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.69%. Comparing base (55ecd10) to head (5cd8753).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6739      +/-   ##
==========================================
+ Coverage   79.67%   79.69%   +0.02%     
==========================================
  Files         565      565              
  Lines       63376    63376              
==========================================
+ Hits        50494    50509      +15     
+ Misses       9895     9884      -11     
+ Partials     2987     2983       -4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[ktgowtham]

We generally get confirmation from team members of any pending PRs before cutting a release. So with scheduled action, we might sometimes need to cut it again, if team members aren't ready.
I'm fine keeping it manual for now.
But thanks for this PR, we don't need to do these steps manually now. Also avoids any typo issues when creating branches.