Update dependabot-merger to tag on-call engineer

[nsingh-branch]

Description

Updated the GHA to also get the current on-call engineer and tag them in the Slack message.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Ran with Act locally.

• Unit test
• Integration test

JS Budget Check

Please mention the size in kb before abd after this PR

Files	Before	After
dist/build.js.
dist/build.min.js

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

Mentions:

List the person or team responsible for reviewing proposed changes.

cc @BranchMetrics/saas-sdk-devs for visibility.

[github-actions]

Test Results

112 tests   105 ✔️  55s ⏱️
    1 suites      7 💤
    1 files        0 ❌

Results for commit 52f713f.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@9da1bbe). Click here to learn what that means.
The diff coverage is n/a.

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