fix(cubesql): Support Z postfix in Timestamp response transformation

[MazterQyou]

Check List

• Tests has been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Description of Changes Made

This PR extends Timestamp response transformation, supporting Z suffix variant.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (f24554b) 79.12% compared to head (f984ad4) 67.88%.
Report is 5 commits behind head on master.

Files	Patch %	Lines
rust/cubesql/cubesql/src/compile/engine/df/scan.rs	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #7774       +/-   ##
===========================================
- Coverage   79.12%   67.88%   -11.25%     
===========================================
  Files         191      345      +154     
  Lines       37154    58124    +20970     
  Branches        0     5394     +5394     
===========================================
+ Hits        29398    39455    +10057     
- Misses       7756    17922    +10166     
- Partials        0      747      +747     

Flag	Coverage Δ
cube-backend	47.95% <ø> (?)
cubesql	79.12% <50.00%> (-0.01%)	⬇️

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