update phpstan key

Author: ashnazg

.travis.yml

@@ -26,7 +26,7 @@ jobs:
       php: 7.1
       before_script:
         - travis_retry wget --no-verbose https://phar.io/releases/phive.phar
-        - travis_retry php phive.phar --no-progress install --trust-gpg-keys 8E730BA25823D8B5 phpstan
+        - travis_retry php phive.phar --no-progress install --trust-gpg-keys CF1A108D0E7AE720 phpstan
       script:
         - ./tools/phpstan analyse src --level max --configuration phpstan.neon