Currently addExecutable is called 3 times, unnecessarily making the code
more complex.
The method takes as argument the path to the exercises directory.
Additionally, use the new std.Build.ExecutableOptions.link_libc field.
The new field was added in ziglang/zig@adc9b77d5f on 2023-04-13.
Update the required Zig compiler version.
Note that I added the **current** zig version to the changelog, since
the reason for the change is known only to the person updating the
version.
69103a3b82