ci: add release workflow to publish new tags to LuaRocks (#1431)

Co-authored-by: hrsh7th <629908+hrsh7th@users.noreply.github.com>

nvim-cmp-scm-1.rockspec

@@ -18,21 +18,14 @@ dependencies = {
 }
 
 source = {
-  url = 'http://github.com/hrsh7th/nvim-cmp/archive/v' .. MODREV .. '.zip',
-  dir = 'nvim-cmp-' .. MODREV,
+  url = 'git://github.com/hrsh7th/nvim-cmp',
 }
 
-if MODREV == 'scm' then
-  source = {
-    url = 'git://github.com/hrsh7th/nvim-cmp',
-  }
-end
-
 build = {
   type = 'builtin',
   copy_directories = {
     'autoload',
-    'doc',
-    'plugin'
+    'plugin',
+    'doc'
   }
 }