chore: GH action for testing without libopusfile

.github/workflows/test.yml

@@ -1,7 +1,7 @@
 on: [push, pull_request]
 name: Test
 jobs:
-  test:
+  full:
     strategy:
       matrix:
         go-version:
@@ -24,4 +24,18 @@ jobs:
     - name: Lint
       run: gofmt -d . | tee /dev/stderr | ifne false
     - name: Test
-      run: go test -race -v ./...
+      run: go test -race -v ./...
+
+  no-libopusfile:
+    runs-on: ubuntu-20.04
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: 1.14.x
+    - name: Install system dependencies
+      run: sudo apt-get install pkg-config libopus-dev
+    - name: Checkout code
+      uses: actions/checkout@v2
+    - name: Test
+      run: go test -tags nolibopusfile -race -v ./...