Update documentation with latest version references

[Copilot]

This PR updates outdated version references in the documentation to reflect the current state of the project.

Changes Made

• Updated installation examples in README.md from v0.12.9 to v0.12.12 to match the latest release
• Ensured consistency between installation instructions and actual available versions

Background

The README.md contained outdated version references in the installation section that pointed to v0.12.9, while the latest release is v0.12.12. This could confuse users who might try to install a specific version that's no longer the most current.

Testing

• Verified that Sphinx documentation builds successfully after the changes
• Confirmed that all version references are now consistent with the latest release
• Maintained the existing v0.11.3 reference in the breaking changes section as it serves a different purpose (showing users how to stay on the older branch)

This is a minimal documentation maintenance update to keep installation instructions current with the project's releases.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• foundation.wikimedia.org
  • Triggering command: curl -s -o /dev/null -w %{http_code} REDACTED (dns block)
• wikibaseintegrator.readthedocs.io
  • Triggering command: curl -s -o /dev/null -w %{http_code} REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.