GUI Table: Do not set item value if same as current value

[linwang9926]

Description

Fix the issue #1013 . Users can keep their node name while double click the item name.

Types of changes

• Bugfix
• New feature
• Refactor / Code style update (no logical changes)
• Build / CI changes
• Documentation Update
• Other (explain)

Does this address any currently open issues?

• Double clicking editable item in table and then clicking elsewhere removes item #1013

Outside contributors checklist

• Review the guidelines for contributing to this repository
• Read and sign the CLA and add yourself to the authors list
• Make sure you are making a pull request against the develop branch (not main). Also you should start your branch off develop
• Add tests that prove your fix is effective or that your feature works
• Add necessary documentation (if appropriate)

Thank you for contributing to SLEAP!

❤️

[roomrys]

Nit pick: change item_name to item_value

[codecov]

Codecov Report

Merging #1022 (5f997da) into develop (7ca3918) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #1022      +/-   ##
===========================================
- Coverage    66.77%   66.75%   -0.02%     
===========================================
  Files          127      127              
  Lines        21508    21514       +6     
===========================================
  Hits         14362    14362              
- Misses        7146     7152       +6     

Impacted Files	Coverage Δ
sleap/gui/dataviews.py	79.41% <0.00%> (-1.59%)	⬇️

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