Set CWE-134 from 9.3 to 7.3 CVSS score for memory safe languages

- Sync up to score given to javascript/ruby

java/ql/src/Security/CWE/CWE-134/ExternallyControlledFormatString.ql

@@ -3,7 +3,7 @@
  * @description Using external input in format strings can lead to exceptions or information leaks.
  * @kind path-problem
  * @problem.severity error
- * @security-severity 9.3
+ * @security-severity 7.3
  * @precision high
  * @id java/tainted-format-string
  * @tags security