Add a rudimentary deps.edn file

This PR just adds a deps.edn file with the necessary dependencies specified in order to allow one to depend on Loom via git deps. Relevant issue is here https://github.com/aysylu/loom/issues/135

I tested it in my project by including the following coordinates in my project's deps file:

aysylu/loom {:git/url "https://github.com/cjsauer/loom.git"
             :sha     "acd15ed3136a0f4091e97bfc187764ff8b60da4e"}

This worked fine in both CLJ and CLJS (my project is CLJC).