C++: Fix change note category

Author: jketema

cpp/ql/lib/change-notes/2026-07-23-std-regex-ecmascript-parser.md

@@ -1,4 +1,4 @@
 ---
-category: minorAnalysis
+category: feature
 ---
 * Added a C++ regular-expression parser for the ECMAScript grammar used by `std::regex`.