Remove stray : in instance form

[knolleary]

Noticed the Blueprint header in the instance form has a trailing : - but none of the other fields does.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.52%. Comparing base (b7548c5) to head (31c13ad).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3984   +/-   ##
=======================================
  Coverage   78.52%   78.52%           
=======================================
  Files         284      284           
  Lines       12945    12945           
  Branches     2886     2886           
=======================================
  Hits        10165    10165           
  Misses       2780     2780           

Flag	Coverage Δ
backend	78.52% <ø> (ø)

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