…IString() (python#146201)Avoid calling memcpy(data + writer->pos, NULL, 0)which has an undefined behavior.Co-authored-by: Victor Stinner <vstinner@python.org>(cherry picked from commitcd10a2e)

…IIString() (#146201) (#146220)gh-146196: Fix Undefined Behavior in _PyUnicodeWriter_WriteASCIIString() (#146201)Avoid calling memcpy(data + writer->pos, NULL, 0)which has an undefined behavior.(cherry picked from commitcd10a2e)Co-authored-by: Shamil <ashm.tech@proton.me>

* upstream/main: (1475 commits)  Docs: replace all `datetime` imports with `import datetime as dt` (python#145640)pythongh-146153: Use `frozendict` in pure python fallback for `curses.has_key` (python#146154)pythongh-138234: clarify returncode behavior for subprocesses created with `shell=True` (python#138536)pythongh-140947: fix contextvars handling for server tasks in asyncio  (python#141158)pythonGH-100108: Add async generators best practices section (python#141885)pythonGH-145667: Merge `GET_ITER` and `GET_YIELD_FROM_ITER` (pythonGH-146120)pythongh-146228: Better fork support in cached FastPath (python#146231)pythongh-146227: Fix wrong type in _Py_atomic_load_uint16 in pyatomic_std.h (pythongh-146229)pythongh-145980: Fix copy/paste mistake in binascii.c (python#146230)pythongh-146092: Raise MemoryError on allocation failure in _zoneinfo (python#146165)pythongh-91279: Note `SOURCE_DATE_EPOCH` support in `ZipFile.writestr()` doc (python#139396)pythongh-146196: Fix Undefined Behavior in _PyUnicodeWriter_WriteASCIIString() (python#146201)pythongh-143930: Reject leading dashes in webbrowser URLspythongh-145916: Soft-deprecate ctypes.util.find_library (pythonGH-145919)pythongh-146205: Check the errno with != 0 in close impls in select module (python#146206)pythongh-146171: Fix nested AttributeError suggestions (python#146188)pythongh-146099: Optimize _GUARD_CODE_VERSION+IP via function version symbols (pythonGH-146101)pythongh-145980: Add support for alternative alphabets in the binascii module (pythonGH-145981)pythongh-145754: Update signature retrieval in unittest.mock to use forwardref annotation format (python#145756)pythongh-145177: Add emscripten run --test, uses test args from config.toml (python#146160)  ...