Buffer delay text cut off

**Describe the bug**
When choosing a buffer delay that is different from the predefined 64, 128 or 256, the text is cut off.

**To Reproduce**
On linux: start Jack with buffer size 1024
`jackd -d dummy -p 1024`
Start jamulus and open the settings window
Observe the cut off closing parenthesis.

**Expected behavior**
Text should not get cut off

**Screenshots**

**Operating system**
Ubuntu 20.10

**Version of Jamulus**
both 3.7.0 and latest master

**Additional context**
Seems to happen independent from the selected UI language.

Reproduce the issue by starting JACK with `jackd -d dummy -p 1024`, then opening Jamulus's settings window on Linux. Inspect the buffer-delay text shown for a non-predefined value such as 1024, and verify that the closing parenthesis is fully visible across the reported UI languages.

Written by the indexing model from the issue text.