wip: fix mqtt3 compile error #1271

Job	Run time
linux-compat (manylinux1-x64)	2m 30s
linux-shared-libs	2m 45s
linux-compat (manylinux2014-x86)	2m 36s
linux-compat (manylinux1-x86)	2m 34s
clang-sanitizers (,thread)	3m 51s
linux-compat (al2-x64)	2m 37s
linux-compat (opensuse-leap)	2m 37s
linux-compat (rhel8-x64)	2m 39s
linux-compat (manylinux2014-x64)	2m 27s
clang-sanitizers (,address,undefined)	3m 35s
linux-compiler-compat (clang-9)	2m 58s
linux-compiler-compat (clang-6)	2m 57s
linux-compat (fedora-34-x64)	2m 32s
windows	3m 45s
linux-compiler-compat (clang-8)	2m 57s
linux-compiler-compat (gcc-6)	2m 58s
linux-compiler-compat (clang-15)	2m 54s
windows-app-verifier	3m 52s
linux-compiler-compat (clang-17)	2m 54s
linux-compiler-compat (gcc-4.8)	2m 41s
linux-compiler-compat (clang-11)	2m 58s
linux-compiler-compat (gcc-8)	2m 53s
linux-compiler-compat (gcc-7)	2m 41s
linux-compiler-compat (clang-10)	2m 54s
macos (dispatch_queue)	1m 8s
linux-compiler-compat (gcc-11)	2m 54s
macos (kqueue)	1m 32s
linux-compiler-compat (gcc-5)	2m 39s
macos-x64	1m 38s
windows-vc17 (x64)	3m 34s
windows-vc17 (x86)	3m 28s
downstream	2m 52s
windows-shared-libs	3m 29s
	1h 33m 19s

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