[release] prepare a bug-fix release per but found by @Victorious3 (#198)

CHANGELOG.rst

@@ -12,9 +12,14 @@ The format of this *Change Log* is inspired by `keeapachangelog.org`_.
 
 `X.Y.Z`_ @ 2021
 ---------------
-.. _`X.Y.Z`: https://github.com/apalala/tatsu/compare/v5.6.0...master
+.. _`X.Y.Z`: https://github.com/apalala/tatsu/compare/v5.6.1...master
 
 
+`5.6.1`_ @ 2021-03-22
+---------------------
+.. _`5.6.0`: https://github.com/apalala/tatsu/compare/v5.6.0...v5.6.1
+
+*   Fix bug in which rule fields were forced on empty ``AST`` (`@Victorious3`_)
 
 `5.6.0`_ @ 2021-03-21
 ---------------------
@@ -68,7 +73,7 @@ The format of this *Change Log* is inspired by `keeapachangelog.org`_.
 *   Allow empty patterns (``//``) like Python does
 *  `#65`_ Allow initial, consecutive, and trailing ``@namechars``
 *  `#73`_ Allow ``@@whitespace :: None`` and ``@@whitespace :: False``
-*  `#75`_ Complete implemenation of left recursion(`@Victorious3`_)
+*  `#75`_ Complete implemenation of left recursion (`@Victorious3`_)
 *  `#77`_ Allow ``@keyword`` throughout the grammar
 *  `#89`_ Make all attributes defined in the rule present in the resulting ``AST`` or ``Node`` even if the associated expression was not parsed
 *  `#93`_ Fix trace colorization on Windows

README.md

@@ -9,8 +9,8 @@
 ``` python
 def WARNING():
     """
-    TatSu==5.6.0 requires Python>=3.8
-    TatSu>=5.7.0 will require Python>=3.9
+    TatSu>=5.6 requires Python>=3.8
+    TatSu>=5.7 will require Python>=3.9
 
     Python 3.8 and 3.9 introduced new language features that allow
     writing better programs more clearly. All code written for

README.rst

@@ -22,8 +22,8 @@
 
     def WARNING():
         """
-        TatSu==5.6.0 requires Python>=3.8
-        TatSu>=5.7.0 will require Python>=3.9
+        TatSu>=5.6 requires Python>=3.8
+        TatSu>=5.7 will require Python>=3.9
 
         Python 3.8 and 3.9 introduced new language features that allow
         writing better programs more clearly. All code written for

tatsu/_config.py

@@ -1,2 +1,2 @@
 __toolname__ = 'TatSu'
-__version__ = '5.6.0'
+__version__ = '5.6.1'

tatsu/collections/orderedset.py

@@ -22,7 +22,7 @@ def __init__(self, iterable: Optional[Iterable[T]] = None):
             self._map = dict.fromkeys(iterable)  # type: Dict[T, int]
         else:
             self._map = {}
-        self._list_cache: Optional[list[T]] = None
+        self._list_cache: Optional[Sequence[T]] = None
 
     def __len__(self):
         return len(self._map)