Use develop branch of Rain library in Travis CI

.travis.yml

@@ -20,9 +20,16 @@ cache:
     - $HOME/.composer/cache/files
 
 install:
-  - travis_retry composer install --no-interaction --no-progress --no-suggest
-
-before_script: git reset --hard HEAD
+  - composer install --no-interaction --no-progress --no-suggest
+  # Reset October modules back to Git source
+  - git reset --hard HEAD
+  # Replace October library with `develop` branch
+  - rm -rf ./vendor/october/rain
+  - wget https://github.com/octobercms/library/archive/develop.zip -O ./vendor/october/develop.zip
+  - unzip ./vendor/october/develop.zip
+  - mv ./vendor/october/library-develop ./vendor/october/rain
+  # Dump autoload
+  - composer dump-autoload
 
 stages:
   - test