chore(deps): update dependency sphinx-rtd-theme to ~1.3

This MR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
sphinx-rtd-theme	~1.0 -> ~1.3

---

Release Notes

readthedocs/sphinx_rtd_theme (sphinx-rtd-theme)

v1.3.0

Compare Source

v1.2.2

Compare Source

v1.2.1

Compare Source

v1.2.0

Compare Source

v1.1.1

Compare Source

v1.1.0

Compare Source

---

Configuration

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

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Never, 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.