Add v1.x deprecation warning

[mfisher87]

Closes #545

[github-actions]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.20%. Comparing base (bea9fe0) to head (c6811c7).
Report is 1 commits behind head on development.

❗ There is a different number of reports uploaded between BASE (bea9fe0) and HEAD (c6811c7). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (bea9fe0)	HEAD (c6811c7)
	3	2

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #603      +/-   ##
===============================================
- Coverage        71.57%   65.20%   -6.37%     
===============================================
  Files               37       37              
  Lines             3061     3064       +3     
  Branches           596      596              
===============================================
- Hits              2191     1998     -193     
- Misses             766      981     +215     
+ Partials           104       85      -19     

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[mfisher87]

I really wish I had more time to get the integration test workflow all smoothed out. Not sure what's going on :(

[JessicaS11]

Re-reviewing after merges from development to see if it triggers UML+integration tests