Require magit - not sure on this one

Since the only reference is inside of a hook, and only as a default value, do we
actually require this?  It's going to usually succeed at runtime.  I can add the
requirement to the test.  I do anticipate doing more magit integration in the
future, such as jumping to tests form magit buffers (should just work actually)

Anyway.  Everyone has it.  No harm, no foul.

Signed-off-by: Psionik K <73710933+psionic-k@users.noreply.github.com>

lisp/erk.el

@@ -55,6 +55,7 @@
 (require 'finder)
 (require 'license-templates)
 (require 'lisp-mnt)
+(require 'magit)
 (require 'project)
 (require 'vc)
 (require 'org)