upgrade to latest sdk

[alessio]

As per changes introduced with cosmos/cosmos-sdk#4602

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.
• Wrote tests
• Updated relevant documentation (docs/)
• Added a relevant changelog entry: clog add [section] [stanza] [message]
• Reviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge PR #XYZ: [title]" (coding standards)

[codecov-io]

Codecov Report

Merging #52 into master will increase coverage by 0.43%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #52      +/-   ##
==========================================
+ Coverage   66.88%   67.31%   +0.43%     
==========================================
  Files           5        5              
  Lines         465      465              
==========================================
+ Hits          311      313       +2     
+ Misses        123      121       -2     
  Partials       31       31