sky130hd/ibex: tighten due to 0 tns

| Metric                                        | Old      | New      | Type     |
| ------                                        | ---      | ---      | ----     |
| globalroute__antenna_diodes_count             |       70 |      302 | Failing  |
| detailedroute__route__wirelength              |   743158 |   897255 | Failing  |
| detailedroute__antenna_diodes_count           |       20 |       74 | Failing  |
| finish__timing__setup__ws                     |    -0.27 |    -2.06 | Failing  |
| finish__timing__drv__setup_violation_count    |      926 |     1139 | Failing  |
| finish__timing__wns_percent_delay             |    -10.0 |   -29.67 | Failing  |

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

Author: maliberty

flow/designs/sky130hd/ibex/constraint.sdc

@@ -2,7 +2,7 @@ current_design ibex_core
 
 set clk_name  core_clock
 set clk_port_name clk_i
-set clk_period 15.0
+set clk_period 10.0
 set clk_io_pct 0.2
 
 set clk_port [get_ports $clk_port_name]