Update to "tmpl" template repository version 0.5.0 (#23)

Update to "tmpl" version 0.5.0 [1] which now uses namespace for the NPM
package name [2] that help to prevent collisions with already existing
NPM packages like tmpl [3].

[1]: https://github.com/svengreb/tmpl/releases/tag/v0.5.0
[2]: svengreb/tmpl#48
[3]: https://www.npmjs.com/package/tmpl

Closes GH-22

package.json

@@ -1,5 +1,5 @@
 {
-  "name": "tmpl-go",
+  "name": "@svengreb/tmpl-go",
   "version": "0.3.0",
   "description": "A repository template for Go projects",
   "author": {