Add missing backslash in make-release.sh

[dkwon17]

What does this PR do?

Adds missing backslash in the make-release script.

What issues does this PR fix or reference?

The missing backslash causes the error in the following github action: https://github.com/devfile/devworkspace-operator/actions/runs/20727988253/job/59508350980

./make-release.sh: line 146: -e: command not found

Is it tested? How?

PR Checklist

• E2E tests pass (when PR is ready, comment /test v8-devworkspace-operator-e2e, v8-che-happy-path to trigger)
  • v8-devworkspace-operator-e2e: DevWorkspace e2e test
  • v8-che-happy-path: Happy path for verification integration with Che

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dkwon17

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• OWNERS [dkwon17]

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