Fix badge

Author: baddstats

README.md

@@ -2,7 +2,7 @@
 
 ## Sparse 3-dimensional arrays and linear algebra utilities
 
-[![CRAN status](http://www.r-pkg.org/badges/version/spatstat.sparse)](http://CRAN.R-project.org/package=spatstat.sparse)
+[![CRAN status](https://www.r-pkg.org/badges/version/spatstat.sparse)](http://CRAN.R-project.org/package=spatstat.sparse)
 [![GitHub R package version](https://img.shields.io/github/r-package/v/spatstat/spatstat.sparse)](https://github.com/spatstat/spatstat.sparse)
 ![R-CMD-check](https://github.com/spatstat/spatstat.sparse/workflows/R-CMD-check/badge.svg)
 [![Code Coverage Score](https://codecov.io/github/spatstat/spatstat.sparse/coverage.svg?branch=master)](https://codecov.io/github/spatstat/spatstat.sparse?branch=master)