dev(hansbug): add popitem method for TreeValue

[HansBug]

#44

[codecov]

Codecov Report

Merging #52 (5c6ea4d) into main (17cdc03) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #52   +/-   ##
=======================================
  Coverage   99.24%   99.25%           
=======================================
  Files          35       35           
  Lines        2126     2135    +9     
=======================================
+ Hits         2110     2119    +9     
  Misses         16       16           

Flag	Coverage Δ
unittests	99.25% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
treevalue/tree/common/storage.pyx	100.00% <100.00%> (ø)
treevalue/tree/tree/tree.pyx	100.00% <100.00%> (ø)

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