Fixes for libsndfile

.github/workflows/run-tests.yml

@@ -24,14 +24,14 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python-version }}
-      - name: Install libsndfile if necessary
+      - name: Install libsndfile if necessary (Linux)
         run: |
-          if [ "$RUNNER_OS" == "Linux" ]; then
-            apt install libsndfile1
-          elif [ "$RUNNER_OS" == "macOS" ]; then
-            brew install libsndfile
-          fi
-        shell: bash
+          apt install libsndfile1
+        if: matrix.os == 'ubuntu-latest'
+      - name: Install libsndfile if necessary (macOS)
+        run: |
+          brew install libsndfile
+        if: matrix.os == 'macos-latest'
       - name: Install pyebur128
         run: |
           python -m pip install --upgrade pip