update github actions

Author: mitchellhenke

.github/workflows/main.yml

@@ -28,7 +28,7 @@ jobs:
     - uses: actions/checkout@v2
 
     - name: Setup elixir
-      uses: actions/setup-elixir@v1
+      uses: erlef/setup-elixir@v1
       with:
         elixir-version: ${{ matrix.elixir }} # Define the elixir version [required]
         otp-version: ${{ matrix.otp }} # Define the OTP version [required]