added surface area calculation for pyramid

[tayaswng]

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.95%. Comparing base (8930369) to head (488f36d).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/main/java/com/thealgorithms/maths/Area.java	0.00%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6907      +/-   ##
============================================
- Coverage     78.00%   77.95%   -0.05%     
+ Complexity     6444     6436       -8     
============================================
  Files           737      736       -1     
  Lines         21519    21506      -13     
  Branches       4208     4202       -6     
============================================
- Hits          16785    16765      -20     
- Misses         4062     4070       +8     
+ Partials        672      671       -1     

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