ci: Migrate to new Codecov uploader.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

.github/workflows/zulip-ci.yml

@@ -200,13 +200,9 @@ jobs:
         # Only upload coverage when both frontend and backend
         # tests are ran.
         if: ${{ matrix.include_frontend_tests }}
-        run: |
-          # Codcov requires `.coverage` file to be stored in the
-          # current working directory.
-          mv ./var/.coverage ./.coverage
-          . /srv/zulip-py3-venv/bin/activate || true
-
-          pip install codecov && codecov || echo "Error in uploading coverage reports to codecov.io."
+        uses: codecov/codecov-action@v2
+        with:
+          files: var/coverage.xml,var/node-coverage/lcov.info
 
       - name: Store Puppeteer artifacts
         # Upload these on failure, as well

tools/test-backend

@@ -441,6 +441,7 @@ def main() -> None:
         if options.verbose_coverage:
             print("Printing coverage data")
             cov.report(show_missing=False)
+        cov.xml_report(outfile="var/coverage.xml")
         cov.html_report(directory="var/coverage")
         print("HTML report saved; visit at http://127.0.0.1:9991/coverage/index.html")
     if full_suite and not failures and options.coverage: