chore: add need statement to gitlabci/render_pptx

.gitlab-ci.yml

@@ -42,6 +42,7 @@ render_pdf:
     - if: $CI_COMMIT_BRANCH =~ /^make/
 
 render_ppt:
+  needs: [render_pdf]
   environment: $CI_COMMIT_BRANCH
   stage: build
   when: manual
@@ -77,4 +78,3 @@ pages:
       - public
   rules:
     - if: $CI_COMMIT_BRANCH =~ /^make/
-