Fix Syntax Warning "\d"

src/climpact/convert.py

@@ -78,7 +78,7 @@ class UnitConverter:
                 # try to identify those units and replace numeric values
                 # with a '^' (if numeric characters are present but no
                 # power sign is given - like in m s-1 -> m s^-1)
-                for i in re.findall("[-\d]+", unit[n]):  # noqa: W605
+                for i in re.findall(r"[-\d]+", unit[n]):  # noqa: W605
                     if "^" not in unit[n] or "**" in unit[n]:
                         uu = uu.replace(i, f"^{i}")
             try: