Remove subclassing support from zstd types

Author: AA-Turner

Modules/_zstd/compressor.c

@@ -702,6 +702,6 @@ static PyType_Slot zstdcompressor_slots[] = {
 PyType_Spec zstdcompressor_type_spec = {
     .name = "_zstd.ZstdCompressor",
     .basicsize = sizeof(ZstdCompressor),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     .slots = zstdcompressor_slots,
 };

Modules/_zstd/decompressor.c

@@ -886,6 +886,6 @@ static PyType_Slot ZstdDecompressor_slots[] = {
 PyType_Spec ZstdDecompressor_type_spec = {
     .name = "_zstd.ZstdDecompressor",
     .basicsize = sizeof(ZstdDecompressor),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     .slots = ZstdDecompressor_slots,
 };

Modules/_zstd/zstddict.c

@@ -281,6 +281,6 @@ static PyType_Slot zstddict_slots[] = {
 PyType_Spec zstddict_type_spec = {
     .name = "_zstd.ZstdDict",
     .basicsize = sizeof(ZstdDict),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     .slots = zstddict_slots,
 };