Bump versions to v1.3.0-incubating on release/v1.3

[mengw15]

Task Summary

Bump the project version to 1.3.0-incubating on the release/v1.3 branch,
in preparation for the v1.3.0-incubating release.

Changes (on release/v1.3):

• build.sbt: ThisBuild / version 1.3.0-incubating-SNAPSHOT -> 1.3.0-incubating
• bin/k8s/values.yaml: imageTag 1.3.0-incubating-SNAPSHOT -> 1.3.0-incubating
• frontend/package.json: version 1.3.0-incubating-SNAPSHOT -> 1.3.0-incubating

main then advances to 1.4.0-incubating-SNAPSHOT (same three files, plus the
version dropdown in .github/ISSUE_TEMPLATE/bug-template.yaml, which now also
gains a 1.3.0-incubating (release/v1.3) entry).

The docker-compose bundle pins the image tag via ${IMAGE_TAG} at RC time, so
no change is needed there.

Task Type

• Refactor / Cleanup
• DevOps / Deployment / CI
• Testing / QA
• Documentation
• Performance
• Other

[github-actions]

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