fix: Use semantic heading inside top navigation menu dropdown title

[karmanya79]

Description

Top navigation menudropdown now has corect heading markup rather than using span

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

Base: 92.40% // Head: 92.40% // No change to project coverage 👍

Coverage data is based on head (6ac84b8) compared to base (83c1c9b).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #539   +/-   ##
=======================================
  Coverage   92.40%   92.40%           
=======================================
  Files         571      571           
  Lines       16218    16218           
  Branches     4443     4443           
=======================================
  Hits        14986    14986           
  Misses       1149     1149           
  Partials       83       83           

Impacted Files	Coverage Δ
src/button-dropdown/internal.tsx	100.00% <100.00%> (ø)

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