ctrl_panel: Fix editing fields with unit "°C"

A faulty regular expression within PyQtGraph causes any Parameter with a
suffix that doesn't begin with an alphanumeric character (as matched
with \w) to act abnormally. For instance, entering "100 °C" into the
input boxes gets interpreted as 10 °C.

Patch the FLOAT_REGEX in PyQtGraph to simply match for any character in
the suffix group.

pytec/pytec/gui/view/unitful.py

@@ -1,3 +1,5 @@
+import re
+
 from PyQt6.QtCore import QSignalBlocker
 from PyQt6.QtGui import QValidator
 
@@ -7,6 +9,13 @@ from pyqtgraph.parametertree import registerParameterItemType
 from pyqtgraph.parametertree.parameterTypes import SimpleParameter, NumericParameterItem
 
 
+# See https://github.com/pyqtgraph/pyqtgraph/issues/3115
+fn.FLOAT_REGEX = re.compile(
+    r"(?P<number>[+-]?((((\d+(\.\d*)?)|(\d*\.\d+))([eE][+-]?\d+)?)|((?i:nan)|(inf))))\s*"
+    + r"((?P<siPrefix>[u" + fn.SI_PREFIXES + r"]?)(?P<suffix>.*))?$"
+)
+
+
 class UnitfulSpinBox(SpinBox):
     """
     Extension of PyQtGraph's SpinBox widget.