Create .travis.yml

.github/workflows/.travis.yml

+# R for travis: see documentation at https://docs.travis-ci.com/user/languages/r
+
+language: R
+repos:
+  CRAN: https://cloud.r-project.org
+cache: packages
+latex: false
+pandoc: false
+sudo: false
+install:
+  - Rscript -e "if(!requireNamespace('devtools')) install.packages('devtools')"
+  - Rscript -e "if(!requireNamespace('lucode')) devtools::install_github('pik-piam/lucode')"
+script:
+  - Rscript -e "null <- lucode::codeCheck(strict=TRUE)"