Update python/sdist/amici/include/ symlinks (#3066)

Don't symlink `python/sdist/amici/include/`, as done so far.
Instead, symlink `python/sdist/amici/include/amici`.
This prevents editable installations messing up `include/`.
For example, after an editable installation with scipy-openblas,
the plain c++ build would fail because of a `cblas.h` added to `include/`.

Author: dweindl

python/sdist/amici/_installation/include

@@ -0,0 +1 @@
+../../../../../include/amici