chore(deps): update memcached docker tag to v1.6.40

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

values.yaml

@@ -1685,7 +1685,7 @@ memcached-frontend:
     - -m 1024
   image:
     repository: memcached
-    tag: "1.6.39"
+    tag: "1.6.40"
   metrics:
     enabled: true
     image:
@@ -1710,7 +1710,7 @@ memcached-blocks-index:
     - -m 1024
   image:
     repository: memcached
-    tag: "1.6.39"
+    tag: "1.6.40"
   metrics:
     enabled: true
     image:
@@ -1735,7 +1735,7 @@ memcached-blocks:
     - -m 1024
   image:
     repository: memcached
-    tag: "1.6.39"
+    tag: "1.6.40"
   metrics:
     enabled: true
     image:
@@ -1760,7 +1760,7 @@ memcached-blocks-metadata:
     - -m 1024
   image:
     repository: memcached
-    tag: "1.6.39"
+    tag: "1.6.40"
   metrics:
     enabled: true
     image: