try using newest image with PHP 8.0.9 for Bionic to avoid segfaults w…

…hile running tests with PHP 8

.travis.yml

@@ -11,9 +11,7 @@ jobs:
       php: 7.3
       env: DEPS='lowest' WITH_DOCTRINE_CACHE_BUNDLE='yes' SYMFONY_DEPRECATIONS_HELPER='max[self]=2&max[direct]=168&max[indirect]=871'
     -
-      php: 8.0 # 8.0.2
-#      php: nightly # 8.0.3-dev
-      dist: focal
+      php: 8.0
       env: DEPS='unmodified' WITH_STATIC_ANALYSIS='yes'
 
     - stage: test
@@ -36,17 +34,6 @@ jobs:
     - env: SYMFONY_VERSION='5.4.*' MIN_STABILITY='dev'
   fast_finish: true
 
-before_install:
-  # install a custom PHP version
-  - |
-    if [ "${TRAVIS_PHP_VERSION}" = "8.0" ]; then
-      sudo apt update
-      sudo apt install ca-certificates apt-transport-https software-properties-common
-      sudo add-apt-repository -y ppa:ondrej/php
-      sudo apt install -y php8.0 libapache2-mod-php8.0
-      sudo update-alternatives --config php
-    fi
-
 install:
   # set unlimited memory_limit
   - INI_FILE=~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini