gitlab-ci.yaml: add manual integration test build

Author: borsboom

.gitlab-ci.yml

@@ -21,6 +21,14 @@ build:
     - (cd etc/scripts && stack --install-ghc install --pedantic)
     - stack-release-script check
 
+manual_build:
+  stage: build
+  when: manual
+  script:
+    - export PATH=$HOME/.local/bin:$PATH
+    - (cd etc/scripts && stack --install-ghc install --pedantic)
+    - stack-release-script check
+
 docker_image_lts-8:
   stage: build
   when: manual