Update elixir.yml

.github/workflows/elixir.yml

@@ -7,7 +7,7 @@ jobs:
     - uses: actions/checkout@v2
     - uses: erlef/setup-elixir@v1
       with:
-        otp-version: 23.x
+        otp-version: 24.x
         elixir-version: 1.9.x
     - name: Dependencies
       run: |