Update .travis.yml

.travis.yml

@@ -1,16 +1,20 @@
 language: php
 php:
-  - 7.0
-  - 7.1
-  - 7.2
-  - 7.3
-# - nightly
+  - 7.4
+#  - nightly
 
-before_install:
+sudo: false
+
+cache:
+  directories:
+   - vendor
+
+install:
+- composer require phpunit/phpunit:8.* php-coveralls/php-coveralls:2.*
 - composer install --dev
- 
+
 script:
-- ./vendor/bin/phpunit --coverage-clover ./tests/logs/clover.xml
+- ./vendor/bin/phpunit --coverage-clover tests/logs/clover.xml
 
 after_script:
-- php vendor/bin/coveralls -v
+  - travis_retry php vendor/bin/php-coveralls -v