Remove nostd::span as dependency from Dependency document

[lalitb]

Fixes #1230

Changes

Have validated the two components nostd::span and std::variant. None of these have been copied ( read - lift and shift) directly from the libstd implementation. They have been written to ensure that the ABI compatibility is maintained with libstdc++. The code has been compared with libstd library here and here, and also confirmed with the contributor of std::variant in this repo.

The dependency document has been updated to remove nostd::span as internal dependency.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #1260 (4ca0b53) into main (da94697) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1260   +/-   ##
=======================================
  Coverage   92.37%   92.37%           
=======================================
  Files         202      202           
  Lines        7336     7336           
=======================================
  Hits         6776     6776           
  Misses        560      560