fix: Make user relationship in speaker schema dump_only

[Haider8]

Fixes #7106

Short description of what this resolves:

Speaker schema can receive user relationship which is not needed for POST and PATCH

Changes proposed in this pull request:

Make user relationship in speaker schema dump_only and instead assign current user's id to user relationship.

Checklist

• I have read the Contribution & Best practices Guide and my PR follows them.
• My branch is up-to-date with the Upstream development branch.
• The unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

• All the functions created/modified in this PR contain relevant docstrings.

[codecov]

Codecov Report

Merging #7122 into development will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff              @@
##           development    #7122   +/-   ##
============================================
  Coverage        62.84%   62.84%           
============================================
  Files              262      262           
  Lines            13011    13011           
============================================
  Hits              8177     8177           
  Misses            4834     4834           

Impacted Files	Coverage Δ
app/api/schema/speakers.py	100.00% <ø> (ø)

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[iamareebjamal]

user shouldn't be changed on editing

[iamareebjamal]

Have you tested that user is properly set on creating a speaker

[Haider8]

Yes