allow failures on nightly (#139)

* allow failures on nightly

* also test julia 1.5

* drop unsupported releases

Author: Pietro Vertechi

.travis.yml

@@ -5,10 +5,8 @@ os:
   - osx
 julia:
   - 1.0
-  - 1.1
-  - 1.2
-  - 1.3
   - 1.4
+  - 1.5
   - nightly
 notifications:
   email: false
@@ -17,9 +15,9 @@ git:
 
 ## uncomment the following lines to allow failures on nightly julia
 ## (tests will run but not make your overall status red)
-#matrix:
-#  allow_failures:
-#  - julia: nightly
+matrix:
+ allow_failures:
+ - julia: nightly
 
 ## uncomment and modify the following lines to manually install system packages
 #addons: