Fix plugin path separator on Windows

[jhendersonHDF]

Important

Fixes Windows path separator for _plugin_path in CMakeLists.txt to ensure correct plugin path handling.

• Behavior:
  • Fixes path separator for _plugin_path in CMakeLists.txt on Windows from : to ;.
  • Ensures correct plugin path handling for Windows systems.
• Misc:
  • No changes to Unix/Mac path handling.

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