feat(ci): add GitHub Actions workflow for tests

- create `.github/workflows/test.yml`
- configure workflow to run tests on push to `main`
- use `actions/checkout@v4` and `actions/setup-go@v5`
- run `go test ./...` for testing

Author: alysnnix

.github/workflows/test.yml

@@ -0,0 +1,17 @@
+name: Tests
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - run: go test ./...