ci(deps): update istio helm chart to v1.20.0

[renovate[bot]]

This PR contains the following updates:

Package	Update	Change
base	minor	1.19.3 -> 1.20.0
gateway	minor	1.19.3 -> 1.20.0
istiod	minor	1.19.3 -> 1.20.0

---

Release Notes

istio/istio (base)

### [`v1.20.0`](https://togithub.com/istio/istio/releases/tag/1.20.0): Istio 1.20.0 [Compare Source](https://togithub.com/istio/istio/compare/1.19.4...1.20.0) [Artifacts](http://gcsweb.istio.io/gcs/istio-release/releases/1.20.0/) [Release Notes](https://istio.io/news/releases/1.20.x/announcing-1.20/) ### [`v1.19.4`](https://togithub.com/istio/istio/releases/tag/1.19.4): Istio 1.19.4 [Compare Source](https://togithub.com/istio/istio/compare/1.19.3...1.19.4) [Artifacts](http://gcsweb.istio.io/gcs/istio-release/releases/1.19.4/) [Release Notes](https://istio.io/latest/news/releases/1.19.x/announcing-1.19.4/)

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about these updates again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.