Update action runime to node v16 (#243)

Bumping runtime from node 12 to node 16 within the action container.

Author: max-callstack

action.yml

@@ -50,5 +50,5 @@ outputs:
   response: # id of output
     description: "response from lambda invocation"
 runs:
-  using: "node12"
+  using: "node16"
   main: "dist/index.js"