add test coverage ci with codecov

.github/workflows/coverage.yml

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+name: Coverage
+
+on: [push]
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: ['ubuntu-latest']
+        dart_channel: ['stable']
+
+      fail-fast: false
+    runs-on: ${{ matrix.os }}
+    
+    steps:
+    - uses: actions/checkout@v1
+    - uses: cedx/setup-dart@v2
+      with:
+            release-channel: ${{ matrix.dart_channel }}
+    - run: _tool/test-coverage.sh

_tool/test-coverage.sh

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+#!/bin/bash
+
+set -xeu
+
+cd "${0%/*}"/..
+
+
+pub get
+pub global activate test_coverage
+
+fail=false
+pub global run test_coverage || fail=true
+echo "fail=$fail"
+bash <(curl -s https://codecov.io/bash) -f coverage/lcov.info
+
+test "$fail" == "true" && exit 1
+
+echo "Success 🎉️"
+
+exit 0