Integrate coveralls with github actions

Somehow I thought it worked automatically, but we had to provide the
token.

The configuration is based on Coveralls instructions to run parallel
builds [1].

Alternatively we could use the Coveralls GitHub Action [2] which
slightly simplifies the workflow configuration and removes the
dependency of the coveralls gem. However, it also adds a dependency on
simplecov-lcov and requires configuring it to renerate LCOV files on
each run, so the benefits of using it are not that big.

[1] https://docs.coveralls.io/parallel-build-webhook
[2] https://github.com/coverallsapp/github-action/

.github/workflows/tests.yml

@@ -19,10 +19,13 @@ jobs:
           POSTGRES_USER: consul
           POSTGRES_PASSWORD: ""
     env:
+      CI_BUILD_NUMBER: ${{ github.run_number }}
+      COVERALLS_FLAG_NAME: run-${{ matrix.ci_node_index }}
+      COVERALLS_PARALLEL: true
+      COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
       PGUSER: consul
       POSTGRES_HOST: postgres
       RAILS_ENV: test
-      COVERALLS: true
     strategy:
       fail-fast: false
       matrix:
@@ -55,3 +58,12 @@ jobs:
         with:
           name: screenshots
           path: tmp/screenshots
+  coveralls:
+    runs-on: ubuntu-18.04
+    needs: tests
+    env:
+      CI_BUILD_NUMBER: ${{ github.run_number }}
+      COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
+    steps:
+      - name: Finish coveralls
+        run: curl -k https://coveralls.io/webhook?repo_token=$COVERALLS_REPO_TOKEN -d "payload[build_num]=$CI_BUILD_NUMBER&payload[status]=done"