ci mingw: install Fiddle
ci mingw: install Fiddle

It's for ensuring using the installed system libffi.
It seems that Ruby package in MSYS2 should be rebuilt when libffi
package in MSYS2 is updated.

groonga/groonga,kenhys/groonga,groonga/groonga,kenhys/groonga,kenhys/groonga,kenhys/groonga,kenhys/groonga,groonga/groonga,kenhys/groonga,groonga/groonga,groonga/groonga,groonga/groonga,groonga/groonga,kenhys/groonga,groonga/groonga,kenhys/groonga