feat : add validations

[epicadk]

Description

Fixes #1083

Type of Change:

• Code

Code/Quality Assurance Only

• New feature (non-breaking change which adds functionality pre-approved by mentors)

How Has This Been Tested?

ran tests

Checklist:

• [x] My PR follows the style guidelines of this project
• [x] I have performed a self-review of my own code or materials

Code/Quality Assurance Only

• [x] My changes generate no new warnings
• [x] My PR currently breaks something (fix or feature that would cause existing functionality to not work as expected)
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been published in downstream modules

[codecov[bot]]

Codecov Report

Merging #1096 (e0af4f7) into develop (ee009cf) will increase coverage by 0.09%. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #1096      +/-   ##
===========================================
+ Coverage    92.90%   93.00%   +0.09%     
===========================================
  Files           38       38              
  Lines         2073     2102      +29     
===========================================
+ Hits          1926     1955      +29     
  Misses         147      147              

Impacted Files	Coverage Δ
app/database/models/mentorship_relation.py	100.00% <100.00%> (ø)
app/database/models/task_comment.py	96.15% <100.00%> (+0.69%)	:arrow_up:
app/database/models/user.py	98.79% <100.00%> (+0.22%)	:arrow_up:

[isabelcosta]

@epicadk can you please resolve conflicts here. I'm sorry I've missed this PR, and I am happy to review and approve :)