add missing security severity

Author: erik-krogh

javascript/ql/src/Security/CWE-094/ExpressionInjection.ql

@@ -4,6 +4,7 @@
  *              user to inject code into the GitHub action.
  * @kind problem
  * @problem.severity warning
+ * @security-severity 9.3
  * @precision high
  * @id js/actions/injection
  * @tags actions