v3.8.0

• Speed up module-level one-shot digest(), intdigest(), and
  hexdigest() functions by switching them to METH_FASTCALL.
• Keep one-shot argument handling consistent with hash constructors, including
  positional and keyword input/seed arguments, duplicate argument
  errors, and oversized seed wrapping.
• Fix error handling in the xxh3_128 integer digest path so allocation
  failures are reported cleanly.
• Fix Python 3.8 builds by adding a PyModule_AddType compatibility
  fallback with correct reference counting.
• Correct type stubs for xxh64_digest(), xxh64_hexdigest(), and
  xxh64_intdigest(), they were incorrectly aliased to xxh3_64 functions.

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Full list of changes: v3.7.1...v3.8.0