require CMake 3.8 to understand CXX17 flags - thanks @leeanne2 for reporting

[slayoo]

No description provided.

[github-actions]

CLANG WARNINGS:

error: no input files [clang-diagnostic-error]
error: no such file or directory: '/github/workspace/files/*.cpp' [clang-diagnostic-error]
error: unable to handle compilation, expected exactly one compiler job in '' [clang-diagnostic-error]

CPPCHECK WARNINGS:

CMakeLists.txt:478:5: error: Unmatched '('. Configuration: ''. [syntaxError]
file(GLOB PyPartMC_headers ${CMAKE_SOURCE_DIR}/src/*.hpp)
    ^
clang-tidy-report.txt:3:101: error: syntax error [syntaxError]
error: unable to handle compilation, expected exactly one compiler job in '' [clang-diagnostic-error]
                                                                                                    ^