ci: add coverage report

Signed-off-by: black-desk <me@black-desk.cn>

Author: black-desk

.github/workflows/build-and-test.yaml

@@ -23,3 +23,11 @@ jobs:
         run: |
           make
           make test
+
+      - name: Coverage report
+        run: |
+          export COVERAGE_REPORT=/tmp/io.github.black-desk.cgtproxy-test/coverage.txt &&
+          echo '```' > $GITHUB_STEP_SUMMARY &&
+          make COVERAGE_REPORT=$COVERAGE_REPORT test-coverage &&
+          cat $COVERAGE_REPORT >> $GITHUB_STEP_SUMMARY &&
+          echo '```' >> $GITHUB_STEP_SUMMARY