Try to fix the build

.travis.yml

@@ -1,10 +1,10 @@
 language: php
 
 php:
-    - '7.2'
-    - '7.3'
-    - '7.4'
-    - '8.0snapshot'
+  - '7.2'
+  - '7.3'
+  - '7.4'
+  - '8.0snapshot'
 
 env:
     - SYMFONY_VERSION=4.4.*
@@ -28,7 +28,8 @@ install:
     - composer require --dev symfony/process:${SYMFONY_VERSION} --no-update --no-scripts --prefer-dist
     - composer require --dev symfony/yaml:${SYMFONY_VERSION} --no-update --no-scripts --prefer-dist
 
-    - composer update --prefer-dist --ignore-platform-req=php # ignore-platform-req=php is necessary temporarly because some deps aren't compatible with PHP8 yet
+    # ignore-platform-req=php is necessary temporarily because PageObjectExtension isn't compatible with PHP8 yet: https://github.com/FriendsOfBehat/PageObjectExtension/pull/16
+    - if [[ ${TRAVIS_PHP_VERSION:0:3} == "8.0" ]]; then composer update --prefer-dist --ignore-platform-req=php; else composer update --prefer-dist; fi
 
 script:
     - composer check