fix some unrespected const

src/pyswiftsim_tools.c

@@ -9,7 +9,7 @@ const size_t class_size[class_count] = {
   sizeof(struct cooling_function_data)
 };
   
-const char *class_name[class_count] = {
+char *class_name[class_count] = {
   "UnitSystem",
   "Part",
   "SwiftParams",
@@ -66,7 +66,7 @@ PyObject* pytools_return(void *p, int class)
 
   /* get class information */
   nber_bytes = class_size[class];
-  const char *class_pyname = class_name[class];
+  char *class_pyname = class_name[class];
 
   /* import python class */
   python_class = pytools_import(module_name, class_pyname);
@@ -131,7 +131,7 @@ char* pytools_get_type_name(PyObject *obj)
 char* pytools_construct(PyObject* obj, int class)
 {
   char *module_name = "pyswiftsim.structure";
-  const char *class_pyname;
+  char *class_pyname;
 
   /* check python class */
   if (class >= class_count)

src/pyswiftsim_tools.h

@@ -55,7 +55,7 @@ enum swift_class {
 /* size of each structure in enum swift_class */
 extern const size_t class_size[];
 /* name of each Python class representing a swift class */
-extern const char *class_name[];
+extern char *class_name[];
 
 /* error code in pyswiftsim */
 enum error_code {