docs: add changelog for pr #12773

changes/ce/fix-12773.en.md

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+Upgrade HTTP client libraries.
+
+The HTTP client library (`gun-1.3`) incorrectly appends a `:portnumber` suffix to the `Host` header for
+standard ports (`http` on port 80, `https` on port 443). This could cause compatibility issues with servers or
+gateways performing strict `Host` header checks (e.g., AWS Lambda, Alibaba Cloud HTTP gateways), leading to
+errors such as `InvalidCustomDomain.NotFound` or "The specified CustomDomain does not exist."
+
+