Fix `CLASS` for fill_diode LEF files.

Replace `CLASS SPACER` with `CLASS CORE SPACER`.

Fixes https://github.com/google/skywater-pdk/issues/141.

Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>
tree: 9d2c7e9260a20f015eac52af3366c8c715e3616b
  1. .gitignore
  2. LICENSE
  3. README.rst
  4. cells/
  5. models/
  6. tech/
  7. timing/