Update knn 1.2 to tag in manifest (#1138)

Signed-off-by: John Mazanec <[email protected]>

manifests/1.2.0/opensearch-1.2.0.yml

@@ -46,7 +46,7 @@ components:
       - gradle:dependencies:opensearch.version
   - name: k-NN
     repository: https://github.com/opensearch-project/k-NN.git
-    ref: "1.2"
+    ref: tags/1.2.0.0
     platforms:
       - darwin
       - linux