Update CI workflow to use Codecov for coverage reporting

.github/workflows/build_and_test.yml

@@ -25,12 +25,9 @@ jobs:
 
     - name: Run Unit tests
       run: |
-        go test -race -covermode atomic -coverprofile=covprofile ./...
+        go test -race -covermode atomic -coverprofile=coverage.txt ./... 
 
-    - name: Install goveralls
-      run: go install github.com/mattn/goveralls@latest
-
-    - name: Send coverage
-      env:
-        COVERALLS_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
-      run: goveralls -coverprofile=covprofile -service=github
+    - name: Upload coverage reports to Codecov
+      uses: codecov/codecov-action@v5
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}

README.md

@@ -1,5 +1,5 @@
 [![Go](https://github.com/dhcgn/iot-ephemeral-value-store/actions/workflows/build_and_test.yml/badge.svg)](https://github.com/dhcgn/iot-ephemeral-value-store/actions/workflows/build_and_test.yml)
-[![Coverage Status](https://coveralls.io/repos/github/dhcgn/iot-ephemeral-value-store/badge.svg?branch=main)](https://coveralls.io/github/dhcgn/iot-ephemeral-value-store?branch=main)
+[![codecov](https://codecov.io/gh/dhcgn/iot-ephemeral-value-store/graph/badge.svg?token=LLTOitLLDc)](https://codecov.io/gh/dhcgn/iot-ephemeral-value-store)
 
 # iot-ephemeral-value-store