Fix typo in cacheinit.cmake for h5pl testing

[hyoklee]

blosc -> pl

---

Important

Fixes a typo in cacheinit.cmake, changing h5blosc to h5pl for unit testing configuration.

• Typo Fix:
  • Corrects typo in cacheinit.cmake, changing h5blosc to h5pl in the H5PL_BUILD_TESTING setting.

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