Fix custom check plugins list on checks page

[payton]

This is a very minor change, but when additional custom checks are added, the list of available checks begin to stack. My change just allows them to adjust to a single line.

[codecov[bot]]

Codecov Report

Merging #626 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #626   +/-   ##
=======================================
  Coverage   81.05%   81.05%           
=======================================
  Files          46       46           
  Lines        2930     2930           
  Branches      177      177           
=======================================
  Hits         2375     2375           
  Misses        497      497           
  Partials       58       58

Impacted Files	Coverage Δ
cabot/templates/cabotapp/_statuscheck_list.html	77.09% <100%> (ø)	:arrow_up:

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[frankh]

Thanks 👍