Add Floyd-Warshall algorithm in Java with example usage

[sujith3006]

a) What it does:
Implements Floyd-Warshall algorithm in Java
Includes an example usage with a sample graph
b) Why it’s useful / reason for the PR:
Adds a common shortest-path algorithm to the algorithms repository
Useful for beginners and competitive programmers
c) Any notes / instructions:
File added: FloydWarshall.java
Tested locally on sample graphs
Issue closed #6795

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.80%. Comparing base (f8688ba) to head (b4e14ba).
⚠️ Report is 14 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6795      +/-   ##
============================================
+ Coverage     77.78%   77.80%   +0.01%     
- Complexity     6307     6308       +1     
============================================
  Files           728      728              
  Lines         21012    21012              
  Branches       4097     4097              
============================================
+ Hits          16345    16348       +3     
+ Misses         4022     4021       -1     
+ Partials        645      643       -2     

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[sujith3006]

Please,May I know what's wrong with my code

[github-actions]

This pull request has been automatically closed because its workflows or checks failed and it has been inactive for more than 14 days. Please fix the workflows and reopen if you'd like to continue. Merging from main/master alone does not count as activity.