fsiTools warnings

It seems we get a number of warnings (possibly errors?) during compilation due to
Fortran 2018 dropping support for non-block DO constructs. Brief explanation:
https://stackoverflow.com/questions/63730527/outdated-do-loops-in-fortran-2018

So, rather than messing up the fortran code with editing it,
there is I think an elegant solution:
add_compile_options(-std=legacy) in
physics/femto/fsiTools/CMakeLists.txt file
Doing this removed the warnings for my latest dev build.