fix: use UNION instead of UNION ALL

[CyanVoxel]

Summary

Replaces instances of UNION ALL with UNION to prevent infinite recursive loops in SQL statements. This also aligns with the intended behavior of these statements where the returned results should be unique (at least in library.py). Fixes #875.

From the SQLite docs:

If a UNION operator connects the initial-select with the recursive-select, then only add rows to the queue if no identical row has been previously added to the queue. Repeated rows are discarded before being added to the queue even if the repeated rows have already been extracted from the queue by the recursion step. If the operator is UNION ALL, then all rows generated by both the initial-select and the recursive-select are always added to the queue even if they are repeats. When determining if a row is repeated, NULL values compare equal to one another and not equal to any other value.

Tasks Completed

• Platforms Tested:
  • Windows x86
  • Windows ARM
  • macOS x86
  • macOS ARM
  • Linux x86
  • Linux ARM
• Tested For:
  • Basic functionality
  • PyInstaller executable