* master: (129 commits)
  bpo-43452: Micro-optimizations to PyType_Lookup (pythonGH-24804)
  bpo-43517: Fix false positive in detection of circular imports (python#24895)
  bpo-43494: Make some minor changes to lnotab notes (pythonGH-24861)
  Mention that code.co_lnotab is deprecated in what's new for 3.10. (python#24902)
  bpo-43244: Remove symtable.h header file (pythonGH-24910)
  bpo-43466: Add --with-openssl-rpath configure option (pythonGH-24820)
  Fix a typo in c-analyzer (pythonGH-24468)
  bpo-41561: Add workaround for Ubuntu's custom security level (pythonGH-24915)
  bpo-43521: Allow ast.unparse with empty sets and NaN (pythonGH-24897)
  bpo-43244: Remove the PyAST_Validate() function (pythonGH-24911)
  bpo-43541: Fix PyEval_EvalCodeEx() regression (pythonGH-24918)
  bpo-43244: Fix test_peg_generators on Windows (pythonGH-24913)
  bpo-39342: Expose X509_V_FLAG_ALLOW_PROXY_CERTS in ssl module (pythonGH-18011)
  bpo-43244: Fix test_peg_generator for PyAST_Validate() (pythonGH-24912)
  bpo-42128: Add 'missing :' syntax error message to match statements (pythonGH-24733)
  bpo-43244: Add pycore_ast.h header file (pythonGH-24908)
  bpo-43244: Rename pycore_ast.h to pycore_ast_state.h (pythonGH-24907)
  Remove unnecessary imports in the grammar parser (pythonGH-24904)
  bpo-35883: Py_DecodeLocale() escapes invalid Unicode characters (pythonGH-24843)
  Add PEP 626 to what's new in 3.10. (python#24892)
  ...