Remove dummy spec

spec/nostr_spec.rb

@@ -1,11 +0,0 @@
-# frozen_string_literal: true
-
-RSpec.describe Nostr do
-  it "has a version number" do
-    expect(Nostr::VERSION).not_to be nil
-  end
-
-  it "does something useful" do
-    expect(false).to eq(true)
-  end
-end