Update CHANGELOG.md with dpnp.tensor migration

[vlad-perevezentsev]

This PR adds dpnp.tensor migration entry to CHANGELOG.md and update release summary

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• Have you added documentation for your changes, if necessary?
• Have you added your changes to the changelog?

[antonwolfy]

No more comments from me

[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/index.html

[coveralls]

Coverage is 77.873% — update_changelog_tensor into include-dpctl-tensor. No base build found for include-dpctl-tensor.

[github-actions]

Array API standard conformance tests for dpnp=0.20.0dev6=py313h509198e_59 ran successfully.
Passed: 1357
Failed: 3
Skipped: 16