Pin Spglib version for find package

Nicolas Tancogne-Dejeanrequested to merge
pin_spglib_findpackage into main

Description

FetchContentDeclare first calls find_package, and the version was not pined in this case. More details are discussed in #1199

Checklist

  • I have checked that my code follows the Octopus coding standards
  • I have added tests for all the new features added in this request.

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