internal: simplify the removal of dulicate workspaces.
### Summary:
Refactoring the duplicate removal process for `workspaces` in `fetch_workspaces`.
### Changes Made:
Replaced `[].iter().enumerate().skip(...).filter_map(...)` with a more concise `[i+1..].positions(...)` provided by `itertools`, which enhances clarity without changing functionality
### Impact:
This change aims to enhance the duplicate removal process for `workspaces`. This change has been tested on my machine.
Please review and provide feedback. Thanks!