FIX: Ring oscillator frequency at low pulse widths

This MR addresses the second issue described in #479 (closed) by correcting the formula used to calculate the RO frequency of RD53B.

Now, the configured global pulse width doesn't influence the RO frequency anymore.

A default value of 30 is considered safe, anything larger than 50is not advised, as the RO counters typically start to saturate above this value.

This MR also fixes the pipeline by adding the required pyqtgraph version to setup.py