Fix build for go1.16

[r0x0d]

• Fixed the dependencies for building the code against go1.16
• Added go1.16 as a matrix target for the unit tests
• Updated go.sum to have the correct version of the dependencies

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (281b85f) 61.16% compared to head (1401210) 61.16%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #53   +/-   ##
=======================================
  Coverage   61.16%   61.16%           
=======================================
  Files           5        5           
  Lines         327      327           
=======================================
  Hits          200      200           
  Misses        112      112           
  Partials       15       15           

Flag	Coverage Δ
go-1.16	61.16% <ø> (?)
go-1.20	61.16% <ø> (ø)

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