Add 9.0 branch to the CI branches definition (elastic#16997)

mashhurs · v1v · commit 5a6a8a4486f6 · 2025-02-25T16:45:06.000+01:00
diff --git a/ci/branches.json b/ci/branches.json
@@ -4,6 +4,9 @@
       {
         "branch": "main"
       },
+      {
+        "branch": "9.0"
+      },
       {
         "branch": "8.x"
       },
