Add Kruskal's Algorithm implementation

[RamsaiPolisetti]

Summary

This PR adds an implementation of Kruskal's Minimum Spanning Tree (MST) algorithm to the graph package.
Kruskal’s algorithm is a classic greedy algorithm that finds the MST of a connected, undirected, weighted graph by selecting edges in increasing order of weight while avoiding cycles.

Implementation Details

• Added KruskalsAlgorithm.java under src/main/java/com/thealgorithms/graph/
• Includes:
  • Edge class for representing edges
  • DSU (Disjoint Set Union / Union–Find) for cycle detection
  • kruskalMST() method implementing the core algorithm
• Clean, modular, and follows project style conventions.

Tests

• Added a corresponding JUnit test under
  src/test/java/com/thealgorithms/graph/
• Tests verify:
  • The MST has exactly V - 1 edges.
  • The smallest edges are correctly selected.
  • The algorithm avoids cycles.

All tests pass using ./gradlew test.

Checklist

• Added implementation
• Added tests
• Code compiles successfully
• Tests pass
• Follows coding style and package structure

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 59 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.29%. Comparing base (2c4bf3c) to head (8bbb886).
⚠️ Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
...ava/com/thealgorithms/graph/KruskalsAlgorithm.java	0.00%	59 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7121      +/-   ##
============================================
- Coverage     78.51%   78.29%   -0.23%     
+ Complexity     6752     6751       -1     
============================================
  Files           759      760       +1     
  Lines         22402    22461      +59     
  Branches       4400     4410      +10     
============================================
- Hits          17589    17585       -4     
- Misses         4108     4169      +61     
- Partials        705      707       +2     

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[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.