travis: remove --ignore-platform-reqs and --prefer-lowest on php 8.0

Author: dominikzogg

.travis.yml

@@ -14,10 +14,7 @@ matrix:
     - php: 7.4
       env: composerargs="--prefer-lowest"
     - php: 7.4
-#    - php: 8.0
-#      env: composerargs="--prefer-lowest --ignore-platform-reqs"
     - php: 8.0
-      env: composerargs="--ignore-platform-reqs"
 
 before_script:
   - (phpenv config-rm xdebug.ini || exit 0)