sccfilter: some inherently-weak automata should have t acceptance

* spot/twaalgos/sccfilter.cc: If an inherently-weak automaton has
no rejecting cycle, reduce its acceptance to t instead of Büchi.
* spot/twa/acc.hh (operator==, operator<): Fix comparisons of
true acceptances.
* NEWS: Mention these two changes.
* spot/twaalgos/sccfilter.hh: Update documentation.
* spot/twaalgos/determinize.cc (tgba_determinize): The call
to scc_filter assume that the input BA is never reduced to t
acceptance.  Call scc_filter with an extra option to ensure that.
* spot/twaalgos/postproc.cc (do_scc_filter): Adjust to add the
extra option when we want to build Büchi or coBuchi.
(ensure_ba): Don't mark trivial SCCs as accepting.
* tests/core/complement.test, tests/core/dstar.test,
tests/core/ltlsynt.test, tests/core/readsave.test,
tests/core/wdba2.test, tests/python/_product_susp.ipynb,
tests/python/automata-io.ipynb, tests/python/dualize.py,
tests/python/highlighting.ipynb, tests/python/intrun.py,
tests/python/setacc.py, tests/python/simstate.py,
tests/python/stutter-inv.ipynb, tests/python/zlktree.py: Adjust test
cases.

tests/python/dualize.py

@@ -1,6 +1,6 @@
 #!/usr/bin/python3
 # -*- mode: python; coding: utf-8 -*-
-# Copyright (C) 2017-2019, 2021-2022 Laboratoire de Recherche et
+# Copyright (C) 2017-2019, 2021-2023 Laboratoire de Recherche et
 # Développement de l'EPITA.
 #
 # This file is part of Spot, a model checking library.
@@ -114,7 +114,7 @@ properties: deterministic stutter-invariant very-weak
 --BODY--
 State: 0 {0}
 [t] 0
-State: 1
+State: 1 {0}
 [0] 0
 [!0] 2
 State: 2