fix: explicitely pass CODECOV_TOKEN as covr::codecov() parameter

- Make the intent of the token explicit.
- That way readers can clearly see that CODECOV_TOKEN in a requirement for `covr::codecov()`.

examples/test-coverage.yaml

@@ -31,7 +31,8 @@ jobs:
           covr::codecov(
             quiet = FALSE,
             clean = FALSE,
-            install_path = file.path(normalizePath(Sys.getenv("RUNNER_TEMP"), winslash = "/"), "package")
+            install_path = file.path(normalizePath(Sys.getenv("RUNNER_TEMP"), winslash = "/"), "package"),
+            token = Sys.getenv("CODECOV_TOKEN")
           )
         shell: Rscript {0}