Pass CI var to docker

.gitlab-ci.yml

@@ -18,12 +18,16 @@ test_mkdocs:
 
 test_linter_preview:
     stage: test
-    script: docker run --rm -w /src ${DOCKER_IMAGE} doc.zih.tu-dresden.de/util/lint-changes.sh
+    script:
+        - docker run --rm -w /src -e CI_MERGE_REQUEST_TARGET_BRANCH_NAME ${DOCKER_IMAGE}
+          doc.zih.tu-dresden.de/util/lint-changes.sh
     only: [ merge_requests ]
 
 test_linkchecker_preview:
     stage: test
-    script: docker run --rm -w /src ${DOCKER_IMAGE} doc.zih.tu-dresden.de/util/check-links.sh
+    script:
+        - docker run --rm -w /src -e CI_MERGE_REQUEST_TARGET_BRANCH_NAME ${DOCKER_IMAGE}
+          doc.zih.tu-dresden.de/util/check-links.sh
     only: [ merge_requests ]
 
 test_linter:
@@ -33,7 +37,9 @@ test_linter:
 
 test_linkchecker:
     stage: test
-    script: docker run --rm ${DOCKER_IMAGE} bash -c "find docs -type f -name '*.md' | xargs -L1 markdown-link-check --quiet"
+    script:
+        - docker run --rm ${DOCKER_IMAGE}
+          bash -c "find docs -type f -name '*.md' | xargs -L1 markdown-link-check --quiet"
     only: [ main ]
 
 release: