Fix an import deprecation warning

[calebrob6]

What does this PR do?

Fix an import deprecation warning (collections -> collections.abc). Similar to #3110.

The warning this addresses is:

DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3, and in 3.9 it will stop working
  from collections import Callable

[codecov]

Codecov Report

Merging #8687 (4f86dd2) into master (e5d9e21) will decrease coverage by 4%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #8687    +/-   ##
=======================================
- Coverage      93%     89%    -4%     
=======================================
  Files         167     167            
  Lines       14033   14036     +3     
=======================================
- Hits        13004   12452   -552     
- Misses       1029    1584   +555     

[calebrob6]

(of note: I just searched and this is the only place in the codebase where this class of warnings is happening)

[adamjstewart]

Was literally just about to submit a PR to fix this, thanks @calebrob6!