CI: Fix pure Cpp2 regression tests for MSVC #665

Job	Run time
ubu-24 \| g++-13 \| c++2b \| libstdc++ \| ubuntu-24.04	6m 11s
ubu-24 \| g++-14 \| c++2b \| libstdc++ \| ubuntu-24.04	6m 54s
ubu-24 \| clang++-19 \| c++23 \| libc++-18-dev \| ubuntu-24.04	7m 49s
ubu-24 \| clang++-19 \| c++20 \| libstdc++ \| ubuntu-24.04	7m 46s
mac-13 \| clang++ \| c++2b \| default \| macos-13	5m 10s
ubu-22 \| clang++-15 \| c++20 \| libstdc++ \| ubuntu-22.04	5m 51s
mac-13 \| clang++-15 \| c++2b \| default \| macos-13	10m 32s
win-22 \| cl.exe \| c++latest \| default \| windows-2022	4m 55s
win-22 \| cl.exe \| c++20 \| default \| windows-2022	4m 43s
mac-14 \| clang++ \| c++2b \| default \| macos-14	2m 59s
ubu-22 \| clang++-15 \| c++20 \| libc++-15-dev \| ubuntu-22.04	6m 34s
aggregate-results	6s
	1h 9m 30s

Provide feedback