Auto merge of #12961 - epage:dead, r=weihanglo

refactor(toml): Remove unused method

### What does this PR try to resolve?

While finding better homes for logic for #12801, I found this part of the workspace-inheritance trait was unused.

### How should we test and review this PR?

### Additional information

src/cargo/util/toml/mod.rs

@@ -1548,9 +1548,6 @@ pub trait WorkspaceInherit {
  /// This is the workspace table that is being inherited from.
  /// For example `[workspace.dependencies]` would be the table "dependencies"
  fn inherit_toml_table(&self) -> &str;
-
- /// This is used to output the value of the implementors `workspace` field
- fn workspace(&self) -> bool;
 }
 
 impl<T, W: WorkspaceInherit> schema::MaybeWorkspace<T, W> {
@@ -1598,10 +1595,6 @@ impl WorkspaceInherit for schema::TomlWorkspaceField {
  fn inherit_toml_table(&self) -> &str {
  "package"
  }
-
- fn workspace(&self) -> bool {
- self.workspace
- }
 }
 
 impl schema::TomlWorkspaceDependency {
@@ -1684,10 +1677,6 @@ impl WorkspaceInherit for schema::TomlWorkspaceDependency {
  fn inherit_toml_table(&self) -> &str {
  "dependencies"
  }
-
- fn workspace(&self) -> bool {
- self.workspace
- }
 }
 
 impl<P: ResolveToPath + Clone> schema::TomlDependency<P> {