Update expression in sed command for backport pr workflow

[rak-phillip]

Summary

This updates the sed expression to resolve script failures when backporting PRs.

Occurred changes and/or fixed issues

• Update expression in sed command for backport pr workflow

Technical notes summary

Switching to @ helps sed to distinguish the regular expression from the command's delimiters. The original regular expression was designed to match text with a forward slash which contains a forward slash, which was misinterpreted as the end of the pattern.

Areas or cases that should be tested

This can be tested by creating a file that contains the contents of a PR and manually running the sed command against it:

➤ cat pr_body.txt | sed -E 's@(close|closes|closed|fix|fixes|fixed|resolve|resolves|resolved):?\s+([a-zA-Z09.-]+/[a-zA-Z0-9.-]*)?#[0-9]+\s*,?\s*@Original text redacted by port-pr.yaml @gI'

Areas which could experience regressions

Backport PR workflow.

Screenshot/Video

NA

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes
• The PR has been reviewed in terms of Accessibility
• The PR has considered, and if applicable tested with, the three Global Roles Admin, Standard User and User Base

The merge-base changed after approval.