Update test.yml (#583)

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [ 1.16.x, 1.17.x, 1.19.x, 1.20.x ] # Lowest supported and current stable versions.
+        go-version: [ 1.16.x, 1.17.x, 1.19.x, 1.20.x, 1.21.x ] # Lowest supported and current stable versions.
     runs-on: ubuntu-latest
     steps:
       - name: Install Go
@@ -50,6 +50,6 @@ jobs:
           godog -f progress --strict
       - name: Report on code coverage
         if: matrix.go-version == '1.17.x'
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v3
         with:
           file: ./coverage.txt