Check for Euler's number

Updated is_literal in openscenario_parser.py so that it check for Euler's number.

OpenScenario files exported from RoadRunner contains values with Euler's number.

srunner/tools/openscenario_parser.py

@@ -105,7 +105,7 @@ def is_literal(self) -> bool:
         """
         Returns: True when text is a literal/number
         """
-        return self._is_matching(pattern=r"(-)?\d+(\.\d*)?")
+        return self._is_matching(pattern=r"(-)?\d+(\.\d*)?(e[+-]\d*)?")
 
     def is_parameter(self) -> bool:
         """