Update dependency kubernetes to v21

This MR contains the following updates:

Package	Type	Update	Change
kubernetes	ironbank-pypi	major	20.13.0 -> 21.7.0

---

Release Notes

kubernetes-client/python

v21.7.0

Compare Source

Kubernetes API Version: v1.21.7

Bug or Regression

• Fixed #​741, an issue which prevented Kubernetes cluster api-tokens from exec-plugin auth providers from being refreshed after expiry. (#​250, @​emenendez)
• Use select.poll() for exec on linux/darwin to improve scalability of WSClient (#​268, @​jsun-splunk)

---

Configuration

📅 Schedule: At any time (no schedule defined).

🚦 Automerge: Enabled.

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

🔕 Ignore: Close this MR and you won't be reminded about this update again.

---

• If you want to rebase/retry this MR, check this box.

---

This MR has been generated by Renovate Bot.