Links are broken and older riot release

[agmes4]

Issue

I noticed that the links are all a bit old especially the one in task 7. They lead to nothing with searching the original repo I managed to find them. Also
Also I had issues in task 5 with

/Tutorials/RIOT/sys/fmt/fmt.c:32:36: error: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (17 chars into 16 available) [-Werror=unterminated-string-initialization]
   32 | static const char _hex_chars[16] = "0123456789ABCDEF";
      |      

This is fixed in the latest riot release which is currently not pulled (currently 2023.10 is used).

I fixed most of it already locally but need push access to be able to create a merge request for that.