Use tensorflow 2.0

.travis.yml

@@ -13,7 +13,7 @@ before_install:
   - sudo apt-get -qq update
   - sudo apt-get install -y libgdal-dev libproj-dev python-protobuf libprotoc-dev libprotobuf-dev libv8-dev librsvg2-dev libmpfr-dev
   - sudo pip install pip --upgrade
-  - sudo pip install --ignore-installed numpy pandas keras tensorflow h5py six
+  - sudo pip install --ignore-installed numpy pandas keras tensorflow==2.0 h5py six
   - rcode="tfile <- tempfile(); capture.output(res<-devtools::test(), file = tfile); out <- readLines(tfile); cat(out, sep = '\n'); "
   - rcode+="n.fail <- as.numeric(sub('Failed:[[:space:]]', '', out[grep('Failed:[[:space:]]', out)])); "
   - rcode+="res <- as.data.frame(res); out <- data.frame(file = unlist(res[['file']]), warning = unlist(res[['warning']])); "