Release preparation for version 2.18.2

cpp/ql/src/change-notes/released/1.2.0.md

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+## 1.2.0
+
+### Query Metadata Changes
+
+* The precision of `cpp/unsigned-difference-expression-compared-zero` ("Unsigned difference expression compared to zero") has been increased to `high`. As a result, it will be run by default as part of the Code Scanning suite.
+
+### Minor Analysis Improvements
+
+* Fixed false positives in the `cpp/memory-may-not-be-freed` ("Memory may not be freed") query involving class methods that returned an allocated field of that class being misidentified as allocators.
+* The `cpp/incorrectly-checked-scanf` ("Incorrect return-value check for a 'scanf'-like function") query now produces fewer false positive results.
+* The `cpp/incorrect-allocation-error-handling` ("Incorrect allocation-error handling") query no longer produces occasional false positive results inside template instantiations.
+* The `cpp/suspicious-allocation-size` ("Not enough memory allocated for array of pointer type") query no longer produces false positives on "variable size" `struct`s.