[OpenVINO Backend] support ops.slice_update

[Mohamed-Ashraf273]

Hi @rkazants ,
I've supported ops,silce_update for my GSoC project, but I can't enable tests for it until getting __getitem__ merge.

It could be implemented more easily if we use opset15 instead of opset14.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 90.47619% with 4 lines in your changes missing coverage. Please review.

Project coverage is 82.74%. Comparing base (d16424e) to head (a285aa7).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
keras/src/backend/openvino/core.py	90.47%	1 Missing and 3 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #21362   +/-   ##
=======================================
  Coverage   82.73%   82.74%           
=======================================
  Files         565      565           
  Lines       55215    55257   +42     
  Branches     8606     8614    +8     
=======================================
+ Hits        45682    45721   +39     
- Misses       7424     7425    +1     
- Partials     2109     2111    +2     

Flag	Coverage Δ
keras	82.55% <90.47%> (+<0.01%)	⬆️
keras-jax	63.29% <0.00%> (-0.05%)	⬇️
keras-numpy	58.49% <0.00%> (-0.05%)	⬇️
keras-openvino	33.84% <90.47%> (+0.05%)	⬆️
keras-tensorflow	63.70% <0.00%> (-0.05%)	⬇️
keras-torch	63.32% <0.00%> (-0.05%)	⬇️

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[rkazants]

let us wait until slice_update tests are switched on

[Mohamed-Ashraf273]

@rkazants
I've switched on tests for slice_update.