[skip changelog] Remove unnecessary token input from Codecov upload steps of test workflow (arduino#886)

* Use v1 ref of codecov/codecov-action GitHub Actions action

Previously, the workflow pinned the outdated v1.0.2 ref. The requirement for an upload token has been removed since the 1.0.2 release. Removing the token input will provide several benefits:

- Prevent failures when the workflow is run in forks, which won't have the CODECOV_TOKEN secret defined.
- Allow configuring the workflow to be triggered by pull_request events, making it easy to evaluate the impact the pull request has on code coverage.

The use of the v1 ref, rather than pinning a specific version allows the workflow to automatically benefit from ongoing development work on the action, while still preventing it from being affected by breaking changes.

* Remove unnecessary token input from Codecov upload steps of test workflow

With the modern versions of the codecov/codecov-action GitHub Actions action, the upload token is only required for private repositories. Now that we are using a modern version of the action, this input only has a harmful effect by causing the workflow to fail when run in forks and also preventing us from using Codecov to evaluate the impact on code coverage of pull requests.

Author: per1234

.github/workflows/test.yaml

@@ -77,43 +77,28 @@ jobs:
         run: task test-integration
 
       - name: Send unit tests coverage to Codecov
-        # Since secrets aren't available on forks, we only
-        # upload coverage on `push`. This might change if
-        # Codecov whitelists GitHub, lifting the need
-        # for a token.
         if: >
           matrix.operating-system == 'ubuntu-latest' &&
           github.event_name == 'push'
-        uses: codecov/codecov-action@v1.0.2
+        uses: codecov/codecov-action@v1
         with:
-          token: ${{secrets.CODECOV_TOKEN}}
           file: ./coverage_unit.txt
           flags: unit
 
       - name: Send legacy tests coverage to Codecov
-        # Since secrets aren't available on forks, we only
-        # upload coverage on `push`. This might change if
-        # Codecov whitelists GitHub, lifting the need
-        # for a token.
         if: >
           matrix.operating-system == 'ubuntu-latest' &&
           github.event_name == 'push'
-        uses: codecov/codecov-action@v1.0.2
+        uses: codecov/codecov-action@v1
         with:
-          token: ${{secrets.CODECOV_TOKEN}}
           file: ./coverage_legacy.txt
           flags: unit
 
       - name: Send integration tests coverage to Codecov
-        # Since secrets aren't available on forks, we only
-        # upload coverage on `push`. This might change if
-        # Codecov whitelists GitHub, lifting the need
-        # for a token.
         if: >
           matrix.operating-system == 'ubuntu-latest' &&
           github.event_name == 'push'
-        uses: codecov/codecov-action@v1.0.2
+        uses: codecov/codecov-action@v1
         with:
-          token: ${{secrets.CODECOV_TOKEN}}
           file: ./coverage_integ.txt
           flags: integ