Fixing LEF 'CLASS' on fill cells.

The fill cells should have 'CLASS' of 'CORE SPACER' in the LEF.

All fill cells should now have;
```lef
  CLASS CORE SPACER ;
```

Updating sky130_fd_sc_ls 0.1.1.

Signed-off-by: Tim 'mithro' Ansell <me@mith.ro>
tree: 3bbb030376bb84be9b5c13ec2e9382dd5b8d0475
  1. .gitignore
  2. LICENSE
  3. README.rst
  4. cells/
  5. models/
  6. tech/
  7. timing/