[BUG] Memory over 100GiB displays incorrectly

**Describe the bug**

When the memory goes above 100GiB the fractional part is removed so the length of the numerical string shrinks, but the previous reading is not completely flushed, so there is a leading 9 still visible.
For example
99.9 GiB -> 101 GiB shows up as 9101 GiB

**To Reproduce**

Have lots of ram and use over 100 GiB

**Expected behavior**

It should replace leading characters with spaces or display as 101.0 GiB

**Screenshots**

**Info (please complete the following information):**
- bpytop version: 1.0.67
- psutil version: 5.8.0
- FreeBSD 13.0-RELEASE-p3
- Terminal used: zsh
- Python version, 3.8.10