The current intent of the circleQuestionMark and questionMarkPrefix symbols is to be displayed as circled question marks.
Unlike other symbols, this has an additional problem: this is not displayed correctly on some Linux distributions (like Ubuntu) but is displayed correctly on macOS.

The current logic has several problems. First, the condition platform === 'linux' should be inverted, since it currently shows the circled question mark only on Linux, instead of not on Linux.

Second, it leads replaceSymbols() to replace any normal question mark ? to (?). That's because replaceSymbols() was designed to replace symbols that are easily recognized as "graphical/UI" characters like ✔ or ◀. But ? can be a normal punctuation character, which should not be replaced.

We could use (?) instead of ? as a non-fallback character on Linux, but that removes the ability of replaceSymbols() to replace circled question marks to (?), at least with the current implementation of replaceSymbols().

Sorry if this description is a little confusing. In a nutshell, this module is currently mostly using is-unicode-supported as a switch between fallback and non-fallback characters, and the current logic does not support well OS-specific characters. I initially considered adding a better support for OS-specific characters, but this is more complex that one might think. It appears the simplest solution is to just change the circleQuestionMark and questionMarkPrefix symbols.

Please note that CI tests on the main branch were failing due to this.

This PR implements the following fix: circleQuestionMark and questionMarkPrefix symbols are now always displayed as (?). Before they were displayed as circled question marks on macOS. I am not sure whether this should be considered a breaking change or not.