[BUG] Graph symbols not rendering at uniform width in "Secure Shell App", "hterm"

**Describe the bug**


The graph "pushes" the cores to the right:


**To Reproduce**

run bashtop and leave running.

**Expected behavior**


**Info (please complete the following information):**
Bashtop version: 0.8.29
Linux distribution and version: Linux 4.19.107-Unraid.
Terminal used: Secure Shell App
Font used: Source Code Pro
Bash version, "bash --version" (version 4.4 or above is required): 5.0.11(1)-release (x86_64-slackware-linux-gnu)
Locales: output of "locale -v"
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE=C
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

**Additional context**

contents of `$HOME/.config/bashtop/error.log`

```
New instance of bashtop version: 0.8.29 Pid: 25899

New instance of bashtop version: 0.8.29 Pid: 25783

New instance of bashtop version: 0.8.29 Pid: 23471

New instance of bashtop version: 0.8.29 Pid: 360
```