Update cache action to v3

Author: garaujodev

.github/workflows/elixir.yml

@@ -20,7 +20,7 @@ jobs:
         elixir-version: '1.13.3' # Define the elixir version [required]
         otp-version: '24.2' # Define the OTP version [required]
     - name: Restore dependencies cache
-      uses: actions/cache@v2
+      uses: actions/cache@v3
       with:
         path: deps
         key: ${{ runner.os }}-mix-${{ hashFiles('**/mix.lock') }}