C++: Drop experimental tag from cpp/invalid-pointer-deref

Author: jketema

cpp/ql/src/Security/CWE/CWE-193/InvalidPointerDeref.ql

@@ -8,7 +8,6 @@
  * @id cpp/invalid-pointer-deref
  * @tags reliability
  *       security
- *       experimental
  *       external/cwe/cwe-119
  *       external/cwe/cwe-125
  *       external/cwe/cwe-193