Added Fibonacci program by Aashi Sharma for Hacktoberfest 2025

[aashiisharma]

Added a simple Fibonacci program in Java.
Tested locally and ready to run.
Part of Hacktoberfest 2025 🎉

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.91%. Comparing base (873dd97) to head (5967dc7).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/main/java/fibonacci_series.java	0.00%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6893      +/-   ##
============================================
- Coverage     77.96%   77.91%   -0.05%     
+ Complexity     6431     6430       -1     
============================================
  Files           736      737       +1     
  Lines         21476    21485       +9     
  Branches       4204     4205       +1     
============================================
- Hits          16744    16741       -3     
- Misses         4060     4070      +10     
- Partials        672      674       +2     

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