use elixir 1.13.4

.drone.yml

@@ -21,14 +21,10 @@ steps:
     TEST_DATABASE_URL: ecto://postgres:postgres@database/cannery_test
     HOST: testing.example.tld
   commands:
-  - apk add --no-cache build-base npm git python3
   - mix local.rebar --force
   - mix local.hex --force
   - mix deps.get
-  - mix deps.compile
-  - npm --prefix ./assets ci --progress=false --no-audit --loglevel=error
-  - npm run --prefix ./assets deploy
-  - mix do phx.digest, gettext.extract
+  - npm install --prefix assets
   - mix test
 
 - name: build and publish stable