Update circleci/php Docker tag to v8

Author: renovate-bot

.circleci/config.yml

@@ -6,7 +6,7 @@ version: 2
 jobs:
   php71:
     docker:
-      - image: circleci/php:7.1-cli-node-browsers
+      - image: circleci/php:8.0-cli-node-browsers
     steps:
       - run: sudo pecl install apcu
       - run: sudo docker-php-ext-enable apcu
@@ -16,7 +16,7 @@ jobs:
       - run: php vendor/bin/phpunit --colors=always
   php72:
     docker:
-      - image: circleci/php:7.2-cli-node-browsers
+      - image: circleci/php:8.0-cli-node-browsers
     steps:
       - run: sudo pecl install apcu
       - run: sudo docker-php-ext-enable apcu
@@ -26,7 +26,7 @@ jobs:
       - run: php vendor/bin/phpunit --colors=always
   php73:
     docker:
-      - image: circleci/php:7.3-cli-node-browsers
+      - image: circleci/php:8.0-cli-node-browsers
     steps:
       - run: sudo pecl install apcu
       - run: sudo docker-php-ext-enable apcu
@@ -36,7 +36,7 @@ jobs:
       - run: php vendor/bin/phpunit --colors=always
   php74:
     docker:
-      - image: circleci/php:7.4-cli-node-browsers
+      - image: circleci/php:8.0-cli-node-browsers
     steps:
       - run: sudo pecl install apcu
       - run: sudo docker-php-ext-enable apcu