docs(readme): pin mkdocs-deploy to v1.2.0 commit and bump version refs

[MAfarrag]

Description

Updates the README to reflect the mkdocs/v1.2.0 release of the mkdocs-deploy action.

• Repins the rolling-tag SHA table: mkdocs/v1 now points at the v1.2.0 release commit
  cb1baebe72f571981605ab895a45dae7bfb566ba (was f861b11…).
• Bumps the namespaced-tag version list from mkdocs/v1.1.0 to mkdocs/v1.2.0.
• Updates the "New in" callout to lead with the v1.2.0 inputs (notebooks-exclude,
  notebooks-continue-on-error), while keeping notebook execution attributed to v1.1.0.

Docs-only; no action behaviour changes.

Issues

• Fixes # (n/a — documentation follow-up to the mkdocs/v1.2.0 release)

Type of change

Check relevant points.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Documentation-only change. Verified the pinned SHA resolves to the released tag:

git rev-list -n 1 mkdocs/v1.2.0   # cb1baebe72f571981605ab895a45dae7bfb566ba
git rev-list -n 1 mkdocs/v1       # cb1baebe72f571981605ab895a45dae7bfb566ba

• SHA in the table matches mkdocs/v1.2.0 and the moved mkdocs/v1.
• Version references read mkdocs/v1.2.0.

Checklist:

• updated version number in pyproject.toml. — N/A: actions are released via namespaced git tags.
• added changes to History.rst. — N/A: this repository has no History.rst.
• updated the latest version in README file.
• I have added tests that prove my fix is effective or that my feature works. — N/A: docs-only.
• New and existing unit tests pass locally with my changes. — N/A: docs-only.
• documentation are updated.