gpl: print target density rounded up to two digits
gpl: print target density rounded up to two digits

Previously it was clipped to two digits which might suggest too low a value:

[ERROR GPL-0302] Use a higher -density or re-floorplan with a larger core area.
Given target density: 0.40
Suggested target density: 0.40

vs

[ERROR GPL-0302] Use a higher -density or re-floorplan with a larger core area.
Given target density: 0.40
Suggested target density: 0.41

See OL #999

Signed-off-by: Matt Liberty <44ef1ce0ef6935daf739a0795dad249ba5322e97@eng.ucsd.edu>

QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD