Reinstate the gf180/uart-blocks metric update

It was unrelated to the read_spef problem but fell in the same PR.

| Metric                                        | Old      | New      | Type     |
| ------                                        | ---      | ---      | ----     |
| synth__design__instance__area__stdcell        | 62967.63 |  62967.6 | Tighten  |
| globalroute__antenna_diodes_count             |       13 |       10 | Tighten  |
| detailedroute__route__wirelength              |    20378 |    19722 | Tighten  |
| detailedroute__antenna_diodes_count           |        0 |        5 | Failing  |

Signed-off-by: Matt Liberty <[email protected]>

Author: maliberty