テスト環境のUbuntuのバージョンを20.04に固定

.github/workflows/test.yml

@@ -12,10 +12,10 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest]  # [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-20.04, windows-latest]  # [ubuntu-20.04, macos-latest, windows-latest]
         python: ['3.8.10']
         include:
-        - os: ubuntu-latest
+        - os: ubuntu-20.04
           path: ~/.cache/pip
         # - os: macos-latest
         #   path: ~/Library/Caches/pip
@@ -32,7 +32,7 @@ jobs:
           cache: pip
 
       - name: Install libraries for ubuntu
-        if: matrix.os == 'ubuntu-latest'
+        if: matrix.os == 'ubuntu-20.04'
         run: sudo apt-get install libsndfile1
 
       - name: Install dependencies
@@ -47,20 +47,20 @@ jobs:
           coverage run --omit=test/* -m pytest
 
       - name: Submit coverage to Coveralls
-        if: matrix.os == 'ubuntu-latest'
+        if: matrix.os == 'ubuntu-20.04'
         run: coveralls --service=github
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Create coverage result
-        if: github.event_name == 'pull_request' && matrix.os == 'ubuntu-latest'
+        if: github.event_name == 'pull_request' && matrix.os == 'ubuntu-20.04'
         run: |
           mkdir report
           coverage report > report/report.txt
           echo ${{ github.event.number }} > report/pr_num.txt
 
       - name: Upload coverage result
-        if: github.event_name == 'pull_request' && matrix.os == 'ubuntu-latest'
+        if: github.event_name == 'pull_request' && matrix.os == 'ubuntu-20.04'
         uses: actions/upload-artifact@v3
         with:
           name: report