[ci] Use needs: keyword for DAG.

scripts/ci/jobs/build-gui-linux.yml

 build gui linux:
   extends: .template-build-linux
   stage: gui
+  needs:
+    - job: build linux
+      artifacts: false
   rules:
+    - if: '$CI_MERGE_REQUEST_TARGET_BRANCH_NAME == "master"'
     - changes:
       - Applications/DataExplorer/**/*
-      when: always
     - when: manual
+      allow_failure: true
 
   variables:
     BUILD_DIR: "build-gui-linux"

scripts/ci/jobs/build-gui-mac.yml

 build gui mac:
   extends: .template-build-linux
   stage: gui
+  needs:
+    - job: build mac
+      artifacts: false
   tags:
     - mac
   rules:
+    - if: '$CI_MERGE_REQUEST_TARGET_BRANCH_NAME == "master"'
     - changes:
       - Applications/DataExplorer/**/*
-      when: always
     - when: manual
+      allow_failure: true
 
   variables:
     BUILD_DIR: "build-gui-mac"

scripts/ci/jobs/build-gui-win.yml

 build gui win:
   extends: .template-build-win
   stage: gui
+  needs:
+    - job: build win
+      artifacts: false
   rules:
+    - if: '$CI_MERGE_REQUEST_TARGET_BRANCH_NAME == "master"'
     - changes:
       - Applications/DataExplorer/**/*
-      when: always
     - when: manual
+      allow_failure: true
 
   variables:
     BUILD_DIR: build-gui-win

scripts/ci/jobs/checks.yml

@@ -3,10 +3,10 @@ compiler warnings:
   variables:
     GIT_STRATEGY: none
   allow_failure: true
-  dependencies:
-    - build linux
-    - build win
-    - build mac
+  needs:
+    - job: build linux
+    - job: build win
+    - job: build mac
   script:
     - exit_code=0
     - cd build
@@ -24,10 +24,10 @@ ctest results:
     GIT_STRATEGY: none
   tags:
     - singularity
-  dependencies:
-    - build linux
-    - build win
-    - build mac
+  needs:
+    - job: build linux
+    - job: build win
+    - job: build mac
   script:
     - singularity run docker://$XUNIT_TO_JUNIT_IMAGE -s:./build/Tests/ctest.xml > build/ctest-junit.xml
     - singularity run docker://$XUNIT_TO_JUNIT_IMAGE -s:./build-win/Tests/ctest.xml > build-win/ctest-junit.xml