feat: Test in multiple elixir versions

.gitlab-ci.yml

@@ -15,9 +15,8 @@ variables:
 
 # Test stage. Runs various tests and speculatively builds docker image in
 #   parallel, in case the build passes.
-test:
+.test_template: &test_template
   stage: test
-  image: "elixir:1.10.4-alpine"
   cache:
     paths:
       - _build/
@@ -26,6 +25,18 @@ test:
   - name: postgres:12
   script: script/cibuild
 
+test:
+  <<: *test_template
+  image: "elixir:1.10.4-alpine"
+
+test_1.11.4:
+  <<: *test_template
+  image: "elixir:1.11.4-alpine"
+
+test_1.12.1:
+  <<: *test_template
+  image: "elixir:1.12.1-alpine"
+
 build_image_for_commit:
   stage: test
   image: "docker:20.10"