CI lint-and-test: runs 'mix deps.get' before 'mix format --check-formatted'

Why: Ensures dependencies are up-to-date, which the caching cannot.

Author: DougReeder

.github/workflows/lint-and-test.yml

@@ -193,4 +193,5 @@ jobs:
             _build
           key: mix-${{ hashFiles('mix.lock') }}
 
+      - run: mix deps.get
       - run: mix format --check-formatted '{lib,priv,test,config}/**/*.{ex,exs}'