Adapt to "tmpl-go" template repository version 0.3.0 (#15)

Adapted to "tmpl-go" version 0.3.0 [2] which includes a optimized run
configuration for the CI workflow [2] that helps to improve the
performance though more fine grained configurations:

- Only runs on pushes to the `main` branch.
- Only runs on pushes for `v*` tags.
- Always runs for pushes to PRs.

[2]: svengreb/tmpl-go#18
[1]: https://github.com/svengreb/tmpl-go/releases/tag/v0.3.0

Resolves GH-14

.github/workflows/ci.yml

@@ -4,8 +4,14 @@
 # GitHub Action Workflow for continuous integration jobs.
 # See https://docs.github.com/en/actions and https://github.com/features/actions for more details.
 
-name: CI
-on: [push]
+name: ci
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - v*
+  pull_request:
 
 jobs:
   lint-node: