Fix URLs for release

Author: jimhester

README.md

@@ -2,7 +2,7 @@
 
 <!-- badges: start -->
 [![R-CMD-check](https://github.com/r-lib/cpp11/workflows/R-CMD-check/badge.svg)](https://github.com/r-lib/cpp11/actions)
-[![codecov](https://codecov.io/gh/r-lib/cpp11/branch/main/graph/badge.svg?token=EEWYoCYxQ2)](https://codecov.io/gh/r-lib/cpp11)
+[![codecov](https://app.codecov.io/gh/r-lib/cpp11/branch/main/graph/badge.svg?token=EEWYoCYxQ2)](https://app.codecov.io/gh/r-lib/cpp11)
 [![Lifecycle: stable](https://img.shields.io/badge/lifecycle-stable-brightgreen.svg)](https://lifecycle.r-lib.org/articles/stages.html#stable)
 [![CRAN status](https://www.r-pkg.org/badges/version/cpp11)](https://CRAN.R-project.org/package=cpp11)
 <!-- badges: end -->