[skip changelog] Upgrade workflow ubuntu env (#1159)

Author: silvanocerza

.github/workflows/test.yaml

@@ -8,7 +8,7 @@ jobs:
   test-matrix:
     strategy:
       matrix:
-        operating-system: [ubuntu-latest, windows-latest, macOS-latest]
+        operating-system: [ubuntu-20.04, windows-latest, macOS-latest]
 
     runs-on: ${{ matrix.operating-system }}
 
@@ -69,15 +69,15 @@ jobs:
 
       - name: Run unit tests on the legacy package
         # Run legacy tests on one platform only
-        if: matrix.operating-system == 'ubuntu-latest'
+        if: matrix.operating-system == 'ubuntu-20.04'
         run: task test-legacy
 
       - name: Run integration tests
         run: task test-integration
 
       - name: Send unit tests coverage to Codecov
         if: >
-          matrix.operating-system == 'ubuntu-latest' &&
+          matrix.operating-system == 'ubuntu-20.04' &&
           github.event_name == 'push'
         uses: codecov/codecov-action@v1
         with:
@@ -86,7 +86,7 @@ jobs:
 
       - name: Send legacy tests coverage to Codecov
         if: >
-          matrix.operating-system == 'ubuntu-latest' &&
+          matrix.operating-system == 'ubuntu-20.04' &&
           github.event_name == 'push'
         uses: codecov/codecov-action@v1
         with:
@@ -95,15 +95,15 @@ jobs:
 
       - name: Send integration tests coverage to Codecov
         if: >
-          matrix.operating-system == 'ubuntu-latest' &&
+          matrix.operating-system == 'ubuntu-20.04' &&
           github.event_name == 'push'
         uses: codecov/codecov-action@v1
         with:
           file: ./coverage_integ.txt
           flags: integ
 
   create-test-artifacts:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     needs: test-matrix
 
     steps: