fix: add SGLANG_IS_IN_CI env var to release-docs workflow (#18225)

Co-authored-by: Zeyu Wang <zeyu.wang@yahooinc.com>
Co-authored-by: edwingao28 <edwingao28@users.noreply.github.com>

.github/workflows/execute-notebook.yml

@@ -13,6 +13,8 @@ concurrency:
   group: execute-notebook-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  SGLANG_IS_IN_CI: true
 
 jobs:
   run-all-notebooks:

.github/workflows/release-docs.yml

@@ -14,6 +14,9 @@ concurrency:
   group: release-docs-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  SGLANG_IS_IN_CI: true
+
 jobs:
   execute-and-deploy:
     runs-on: 1-gpu-runner