github: set workflow trigger conditions

.github/workflows/build.yml

@@ -1,6 +1,14 @@
-name: build
+name: Build
 
-on: push
+on:
+  push:
+    tags:
+      - v*
+  workflow_dispatch:
+  workflow_run:
+    workflows: [Test]
+    types:
+      - completed
 
 jobs:
   build_macos:

.github/workflows/test.yml

@@ -0,0 +1,19 @@
+name: Test
+
+on: push
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
+
+    - name: Set up Go
+      uses: actions/setup-go@v4
+      with:
+        go-version: '^1.18'
+
+    - name: Run tests
+      run: make test