Gitlab CI: Specify arm32v7 image for arm32 builds

.gitlab-ci.yml

@@ -228,8 +228,8 @@ arm:
   artifacts: *release-artifacts
   only: *release-only
   tags:
-    - arm32
-  image: elixir:1.10.3
+    - arm32on64
+  image: arm32v7/elixir:1.10.3
   cache: *release-cache
   variables: *release-variables
   before_script: *before-release
@@ -240,8 +240,8 @@ arm-musl:
   artifacts: *release-artifacts
   only: *release-only
   tags:
-    - arm32
-  image: elixir:1.10.3-alpine
+    - arm32on64
+  image: arm32v7/elixir:1.10.3
   cache: *release-cache
   variables: *release-variables
   before_script: *before-release-musl