Ruby: Increase precision of SSRF query

Author: hmac

ruby/ql/src/queries/security/cwe-918/ServerSideRequestForgery.ql

@@ -4,7 +4,7 @@
  * @kind path-problem
  * @problem.severity error
  * @security-severity 9.1
- * @precision medium
+ * @precision high
  * @id rb/request-forgery
  * @tags security
  *       external/cwe/cwe-918