Bump picoCTF-shell-manager submodule
Bump picoCTF-shell-manager submodule

This is necessary following the movement of shell server dependency
installation and configuration over to picoCTF-platform.

Also this bump encompasses a number of stability fixes related to
systemd.

jedav/picoCTF-platform,picoCTF/picoCTF-platform,royragsdale/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,picoCTF/picoCTF-platform,royragsdale/picoCTF,picoCTF/picoCTF,picoCTF/picoCTF,royragsdale/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,royragsdale/picoCTF,jedav/picoCTF-platform,picoCTF/picoCTF,picoCTF/picoCTF,royragsdale/picoCTF