updated yaml

.travis.yml

@@ -1,7 +1,17 @@
 language: R
-sudo: false
 cache: packages
 
+addons:
+  apt:
+    packages:
+    - libglu1-mesa-dev
+
+env:
+  global:
+    - RGL_USE_NULL=TRUE
+    - R_REMOTES_NO_ERRORS_FROM_WARNINGS=true
+    - _R_CHECK_FORCE_SUGGESTS_=false
+
 after_success:
   - Rscript -e 'covr::coveralls()'
   - R CMD INSTALL --build ${PKG_TARBALL}