added tabulation method in nth_fibo problem and memoization method in…

[ojhankit]

… lcs and matrix_mul

Pull Request for PyVerse 💡

Issue Title : Adding methods

• Info about the related issue (Aim of the project) :
• Name: Ankit Ojha
• GitHub ID: ojhankit
• Email ID: ojha27ankit@gmail.com
• Idenitfy yourself: (Mention in which program you are contributing in. Eg. For a WoB 2024 participant it's, WoB Participant)
  gssoc-ext

Closes: #184

Describe the add-ons or changes you've made 📃

Give a clear description of what have you added or modifications made

1. done memoization method for lcs and matrix multiplication problem
   2.tabulation for nth_fibo

Type of change ☑️

What sort of change have you made:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, local variables)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist: ☑️

• My code follows the guidelines of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly wherever it was hard to understand.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added things that prove my fix is effective or that my feature works.
• Any dependent changes have been merged and published in downstream modules.

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