Add deps.edn file

[glts]

This change adds a minimal deps.edn file.

This is required when dependent projects specify their dependency on reducible-stream using Git SHAs. If no deps.edn manifest is present, no clj REPL can be launched:

Error building classpath. Manifest type not detected when finding deps for pjstadig/reducible-stream in coordinate {:git/url "https://github.com/pjstadig/reducible-stream.git", :sha "cb7b5f60faa6b68fea584960efb42586f70f4559"}

Thank you!