v7.29.0

Symbolics v7.29.0

Diff since v7.28.1

Merged pull requests:

• Fix stale undefined exports (Variable, Unknown) (#1906) (@ChrisRackauckas-Claude)
• add hash/isequal for Integral (#1907) (@KristofferC)
• build(deps): bump actions/checkout from 6 to 7 (#1908) (@dependabot[bot])
• Declare public API (unlock downstream ExplicitImports allow-lists) (#1911) (@ChrisRackauckas-Claude)
• Update Project.toml (#1912) (@ChrisRackauckas)