Fixes #231 -- Updated dependency versions

[Narendra-Kamath]

It is observed that the dependency github.com/urfave/cli at a release version of v1.22.0 was having an issue (urfave/cli#888). It was due to the some of the dependency issues with cli, v1.22.1 was released with a fix (urfave/cli#887).

The pull request includes the update of the package dependencies being used in the project. Thus being updated with the dependency versions, will not break the following:

go.exe get -u github.com/aws/aws-lambda-go/cmd/build-lambda-zip

Which includes build using latest available updated versions of dependencies. (Ref: https://github.com/aws/aws-lambda-go/blob/master/README.md)

Solves: #231

[codecov-io]

Codecov Report

Merging #232 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #232   +/-   ##
=======================================
  Coverage   74.44%   74.44%           
=======================================
  Files          20       20           
  Lines         677      677           
=======================================
  Hits          504      504           
  Misses        128      128           
  Partials       45       45

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[Narendra-Kamath]

@bmoffatt please do review.