tests: upgrade protobuf test to use python 3 (#14557)

.github/workflows/unit.yml

@@ -32,17 +32,17 @@ jobs:
     - name: Set up protoc
       uses: arduino/setup-protoc@64c0c85d18e984422218383b81c52f8b077404d3
       with:
-        version: '3.7.1'
+        version: '3.20'
         repo-token: ${{ secrets.GITHUB_TOKEN }}
 
     - name: Set up Python
       uses: actions/setup-python@v1
       with:
-        python-version: 2.7
+        python-version: 3
     - name: Install Python dependencies
       run: |
-        python -m pip install --upgrade pip
-        pip install protobuf==3.7.1
+        python3 -m pip install --upgrade pip
+        pip install protobuf==3.20
 
     - run: yarn install --frozen-lockfile --network-timeout 1000000
     - run: yarn build-report

package.json

@@ -85,8 +85,8 @@
     "computeBenchmarkIndex": "./core/scripts/benchmark.js",
     "minify-latest-run": "./core/scripts/lantern/minify-trace.js ./latest-run/defaultPass.trace.json ./latest-run/defaultPass.trace.min.json && ./core/scripts/lantern/minify-devtoolslog.js ./latest-run/defaultPass.devtoolslog.json ./latest-run/defaultPass.devtoolslog.min.json",
     "save-latest-run": "./core/scripts/save-latest-run.sh",
-    "compile-proto": "protoc --python_out=./ ./proto/lighthouse-result.proto && mv ./proto/*_pb2.py ./proto/scripts || (echo \"❌ Install protobuf ≥ 3.7.1 to compile the proto file.\" && false)",
-    "build-proto-roundtrip": "mkdir -p .tmp && cross-env PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION=2 python proto/scripts/json_roundtrip_via_proto.py",
+    "compile-proto": "protoc --python_out=./ ./proto/lighthouse-result.proto && mv ./proto/*_pb2.py ./proto/scripts || (echo \"❌ Install protobuf = 3.20.x to compile the proto file.\" && false)",
+    "build-proto-roundtrip": "mkdir -p .tmp && python3 proto/scripts/json_roundtrip_via_proto.py",
     "static-server": "node cli/test/fixtures/static-server.js",
     "serve-dist": "cd dist && python3 -m http.server 7878",
     "serve-gh-pages": "cd dist/gh-pages && python3 -m http.server 7333",