Use app.codecov.io as base for codecov link

Author: eddelbuettel

ChangeLog

@@ -1,3 +1,7 @@
+2023-04-18  Dirk Eddelbuettel  <edd@debian.org>
+
+	* README.md: Use app.codecov.io as base for codecov link
+
 2023-04-12  Dirk Eddelbuettel  <edd@debian.org>
 
 	* .github/workflows/ci.yaml: Simplified container use

README.md

@@ -4,7 +4,7 @@
 [![License](https://eddelbuettel.github.io/badges/GPL2+.svg)](https://www.gnu.org/licenses/gpl-2.0.html)
 [![CRAN](https://www.r-pkg.org/badges/version/Rcpp)](https://cran.r-project.org/package=Rcpp)
 [![Dependencies](https://tinyverse.netlify.com/badge/Rcpp)](https://cran.r-project.org/package=Rcpp)
-[![Coverage Status](https://codecov.io/gh/RcppCore/Rcpp/graph/badge.svg)](https://codecov.io/github/RcppCore/Rcpp?branch=master)
+[![Coverage Status](https://codecov.io/gh/RcppCore/Rcpp/graph/badge.svg)](https://app.codecov.io/github/RcppCore/Rcpp?branch=master)
 [![Debian package](https://img.shields.io/debian/v/r-cran-rcpp/sid?color=brightgreen)](https://packages.debian.org/sid/r-cran-rcpp)
 [![Last Commit](https://img.shields.io/github/last-commit/RcppCore/Rcpp)](https://github.com/RcppCore/Rcpp)
 [![Downloads (monthly)](https://cranlogs.r-pkg.org/badges/Rcpp?color=brightgreen)](https://www.r-pkg.org/pkg/Rcpp)