Woodpecker CI: Work around script entrypoint truncation

.woodpecker/unit-testing-elixir-1.18.yaml

@@ -8,9 +8,16 @@ when:
 depends_on:
   - lint
 
+variables:
+  script_file_entrypoint: &script_file_entrypoint
+    - /bin/sh
+    - -c
+    - 'printf "%s" "$CI_SCRIPT" | base64 -d > /tmp/ci-script.sh && /bin/sh -xe /tmp/ci-script.sh'
+
 steps:
   unit-testing-elixir-1.18:
     image: elixir:1.18-otp-27-alpine
+    entrypoint: *script_file_entrypoint
     environment:
       MIX_ENV: test
       DB_HOST: postgres