Fix test-coverage example on Windows

Need to normalize covr install path backslashes.

examples/test-coverage.yaml

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