Function set_workspace_version 

pub fn set_workspace_version(
    manifest: &str,
    from: &str,
    to: &str,
) -> Result<String, BumpEditError>

Rewrite the [workspace.package] version = "<from>" line to to, returning the new manifest text.

Scoped to the [workspace.package] section (the single source of truth for the release version) so a version key in any other table — [package], [dependencies.foo], [workspace.dependencies] — is never touched. Preserves the line’s exact indentation and quote style; only the value between the quotes changes.

Verified against from (llm-review defense-in-depth): the line is rewritten only when its current value is exactly from (the sealed pre-bump version). This makes the edit fail closed on a tree that does not match the plan, and — since the whole-key scan is line-oriented — it also sidesteps a version = "…" occurrence inside a quoted string value (e.g. a description that mentions a version) unless that string happens to equal from, in which case a following real version line still matches.

Errors

BumpEditError::WorkspaceVersionNotFound when the section, or a version = "<from>" line within it, is absent (fail closed rather than write a manifest with no bump).