Declare _strip_comments noexcept for performance reasons

performance hint: src/cpymad/libmadx.pyx:1256:0: Exception check on '_strip_comments' will always require the GIL to be acquired.
Possible solutions:
        1. Declare '_strip_comments' as 'noexcept' if you control the definition and you're sure you don't want the function to raise exceptions.
        2. Use an 'int' return type on '_strip_comments' to allow an error code to be returned.

src/cpymad/libmadx.pyx

@@ -1253,7 +1253,7 @@ cdef clib.variable* _get_var(name) except NULL:
     return var
 
 
-cdef void _strip_comments(char* text) nogil:
+cdef void _strip_comments(char* text) nogil noexcept:
     cdef int in_quotes = 0
     cdef char* dest = text
     cdef char c, d