Add test workflow

.github/workflows/test.yml

@@ -0,0 +1,15 @@
+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.22.x]
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/setup-go@v5
+      with:
+        go-version: ${{ matrix.go-version }}
+    - uses: actions/checkout@v4
+    - run: go build ./cmd/mjwt/
+    - run: go test ./...