Replace call to finalize with GC.gc() to fix tests on julia 1.11

[nhz2]

In Julia 1.11 calling finalize on the Vector from mmap doesn't unmap, because the finalizer is now attached to the internal Memory. Ref: JuliaLang/julia#54210

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.61%. Comparing base (20d6ae7) to head (5d20cb6).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #53   +/-   ##
=======================================
  Coverage   99.61%   99.61%           
=======================================
  Files           6        6           
  Lines         776      776           
=======================================
  Hits          773      773           
  Misses          3        3           

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