python: add bindings for to_generalized_buchi()

* python/spot/impl.i: Here.
* NEWS: Mention it.

NEWS

@@ -10,7 +10,8 @@ New in spot 2.3.1.dev (not yet released)
 
   Python:
 
-  - The bdd_to_formula() function can now be called in Python.
+  - The bdd_to_formula(), and to_generalized_buchi() functions can now
+    be called in Python.
 
   Documentation:
 

python/spot/impl.i

@@ -134,6 +134,7 @@
 #include <spot/twaalgos/neverclaim.hh>
 #include <spot/twaalgos/randomize.hh>
 #include <spot/twaalgos/remfin.hh>
+#include <spot/twaalgos/totgba.hh>
 #include <spot/twaalgos/sccinfo.hh>
 #include <spot/twaalgos/strength.hh>
 #include <spot/twaalgos/sccfilter.hh>
@@ -536,6 +537,7 @@ def state_is_accepting(self, src) -> "bool":
 %include <spot/twaalgos/neverclaim.hh>
 %include <spot/twaalgos/randomize.hh>
 %include <spot/twaalgos/remfin.hh>
+%include <spot/twaalgos/totgba.hh>
 %traits_swigtype(spot::scc_info_node);
 %fragment(SWIG_Traits_frag(spot::scc_info_node));
 %include <spot/twaalgos/sccinfo.hh>