Upgrade package dependencies to fix vulnerability warning

[bwtimm]

Long-overdue bump of all package dependencies to get rid of a known vulnerability warning

[coveralls]

Coverage remained the same at 100.0% when pulling 1a989ac on bt-bump-version into 668a733 on master.

[codecov-io]

Codecov Report

Merging #4 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master     #4   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           6      5    -1     
  Lines          33     29    -4     
=====================================
- Hits           33     29    -4

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