fix cppcheck parser for missing 'file0' in error

[maloel]

Offending error was:

        <error id="preprocessorErrorDirective" severity="error" msg="#error \" verbose="">
            <location file="examples/test_dds/UddsPubSubTypes.h" line="32" column="0"/>
        </error>

And the script (cppcheck-parse.py) crashed:

Traceback (most recent call last):
  File ".github/workflows/cppcheck-parse.py", line 62, in <module>
    file0 = e['file0']
KeyError: 'file0'