docs: Add version-removed for resolve_source

[tiran]

Pull Request Description

What

Add a version removed entry to inform users that the resolve_source hook and default_resolve_source were removed.

Why

See 179c096

• PR follows CONTRIBUTING.md guidelines

[coderabbitai]

📝 Walkthrough

Walkthrough

Documentation update to docs/reference/hooks.rst that adds a stable cross-reference anchor (resolver_provider_hook) before the default_resolver_provider hook definition. A new versionremoved:: 0.80.0 notice was added to the "Source hooks" section indicating that the resolve_source hook and default_resolve_source function have been removed, with a reference directing users to use the resolver_provider hook instead.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change—adding a version-removed notice for the resolve_source hook and default_resolve_source function.
Description check	✅ Passed	The description clearly explains what was added and references the related commit, directly relating to the changeset's purpose.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@docs/reference/hooks.rst`:
- Around line 196-199: The documentation incorrectly states that resolve_source
and default_resolve_source were removed in 0.80.0 while the codebase still
defines resolve_source in src/fromager/sources.py; update the note to reflect
the current state by either removing the .. versionremoved:: 0.80.0 block or
changing it to a deprecation/compatibility note that explains resolve_source
still exists and points users to the newer resolver_provider hook; also replace
the ambiguous reference to "resolver_provider <resolver_provider_hook>" with the
actual callable name get_resolver_provider() so the doc matches the hook API
(mention resolve_source, default_resolve_source, get_resolver_provider, and
resolver_provider hook in the updated text).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: c6c81771-0e46-4ce8-984b-19d45a5721d7

📥 Commits

Reviewing files that changed from the base of the PR and between 7a66afc and a4e4918.

📒 Files selected for processing (1)

• docs/reference/hooks.rst