Bump knex to version 0.20.4 and upgrade vulnerable packages

[mesaugat]

• Use PromiseLike type to comply with knex return types which is incompatible with native Promise type
• Upgrade package: codecov
• Upgrade sub dependencies that were reported as vulnerable

[codecov-io]

Codecov Report

Merging #34 into master will not change coverage.
The diff coverage is 50%.

@@          Coverage Diff           @@
##           master     #34   +/-   ##
======================================
  Coverage    22.9%   22.9%           
======================================
  Files          11      11           
  Lines         179     179           
  Branches       11      11           
======================================
  Hits           41      41           
  Misses        137     137           
  Partials        1       1

Impacted Files	Coverage Δ
src/Connection.ts	0% <0%> (ø)	⬆️
src/util/promise.ts	33.33% <100%> (ø)	⬆️

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