Fix clang-tidy warning 'readability-convert-member-functions-to-static' #955

Job	Run time
Intel LLVM-based compiler	1m 44s
Install on Linux GCC	1m 45s
Install on Linux Clang	1m 50s
Linux clang 18 C++20	5m 39s
Clang tidy on ubuntu-22.04 (Debug)	3m 57s
Linux clang 18	4m 12s
Install on Windows MSVC	2m 56s
Clang tidy on windows-latest (Debug)	5m 50s
Linux clang 18 libc++	3m 8s
Linux clang 17	4m 30s
Clang tidy on ubuntu-22.04 (Release)	3m 52s
Linux clang 17 libc++	2m 49s
Linux clang 16	5m 20s
Clang tidy on windows-latest (Release)	5m 26s
Linux clang 16 libc++	2m 39s
Windows VS v143	5m 17s
Linux clang 15	4m 31s
Linux clang 15 libc++	2m 28s
Windows VS ClangCL	10m 36s
Linux clang 14	4m 42s
Linux clang 14 libc++	2m 24s
Linux clang 13	4m 56s
Linux clang 13 libc++	2m 26s
Linux clang 12	4m 48s
Linux clang 12 libc++	2m 42s
Linux clang 11	5m 14s
Linux clang 11 libc++	2m 45s
Linux clang 10	4m 57s
Linux clang 10 libc++	2m 46s
Linux clang 9 libc++	2m 54s
Linux clang 9	4m 47s
Linux gcc 14 C++20	5m 56s
Linux gcc 14	5m 10s
Linux gcc 13	8m 23s
Linux gcc 12	10m 35s
Linux gcc 11	8m 48s
	2h 42m 42s

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