fix portal_data function and update tests

[ha0ye]

closes #14
manual fix for weecology/portalr#202

[codecov-io]

Codecov Report

Merging #131 into master will increase coverage by 0.06%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #131      +/-   ##
==========================================
+ Coverage   90.17%   90.23%   +0.06%     
==========================================
  Files          14       14              
  Lines         580      584       +4     
==========================================
+ Hits          523      527       +4     
  Misses         57       57

Impacted Files	Coverage Δ
R/get_portal_data.R	100% <100%> (ø)	⬆️
R/get_cowley_data.R	100% <0%> (ø)	⬆️

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