Configure matrix of elixir versions

Author: adam12

.github/workflows/main.yml

@@ -32,9 +32,12 @@ jobs:
         run: mix test
 
   ecto32:
+    strategy:
+      matrix:
+        elixir_version: [1.17, 1.16, 1.15, 1.14, 1.13]
     runs-on: ubuntu-latest
     container:
-      image: elixir:1.17.2
+      image: elixir:${{elixir_version}}
     services:
       postgres:
         image: postgres:14