Update WEAVIATE_126 CI var to latest build

Author: tsmith023

.github/workflows/main.yaml

@@ -9,7 +9,7 @@ on:
 env:
   WEAVIATE_124: 1.24.19
   WEAVIATE_125: 1.25.5
-  WEAVIATE_126: 1.26.0-rc.0
+  WEAVIATE_126: preview--13e65f1
 
 jobs:
   checks: