Update Travis CI configuration

Adds builds on PHP 7.4
Removes HHVM builds
Adds builds with prophecy 1.9 and 1.10

Author: michalbundyra

.travis.yml

@@ -1,13 +1,13 @@
 language: php
 
-sudo: false
-
 cache:
   directories:
     - $HOME/.composer/cache
 
 env:
   - PROPHECY_VERSION=dev-master
+  - PROPHECY_VERSION=~1.10.0
+  - PROPHECY_VERSION=~1.9.0
   - PROPHECY_VERSION=~1.8.0
   - PROPHECY_VERSION=~1.7.0
   - PROPHECY_VERSION=~1.6.0
@@ -19,17 +19,15 @@ env:
   - PROPHECY_VERSION=~1.0.0
 
 php:
+  - 7.4
   - 7.3
   - 7.2
   - 7.1
   - 7.0
   - 5.6
-  - hhvm
 
 matrix:
   fast_finish: true
-  allow_failures:
-    - php: hhvm
 
 install:
   - composer require phpspec/prophecy:${PROPHECY_VERSION} squizlabs/php_codesniffer phpmd/phpmd cundd/test-flight