Download PHP 8.1 from https://downloads.php.net/~patrickallaert/ (#472)

It's the official pre-release location.

See https://www.php.net/archive/2021.php#2021-10-28-2

Author: ruudk

.github/workflows/test.yml

@@ -60,6 +60,9 @@ jobs:
                 librdkafka: 'v0.11.6'
               - php: '7.0.0'
                 librdkafka: 'v0.11.6'
+              - php: '8.1.0RC6'
+                librdkafka: 'master'
+                experimental: true
               - php: '8.0.0'
                 librdkafka: 'master'
                 experimental: true

.github/workflows/test/build-php.sh

@@ -8,8 +8,12 @@ fi
 
 if ! [ -f ~/build-cache/php/usr/local/bin/php ]; then
     echo "PHP build is not cached"
-
-    wget https://secure.php.net/distributions/php-${PHP_VERSION}.tar.bz2
+    
+    case $PHP_VERSION in
+      "8.1"*) wget https://downloads.php.net/~ramsey/php-${PHP_VERSION}.tar.bz2 ;;
+      *)      wget https://secure.php.net/distributions/php-${PHP_VERSION}.tar.bz2 ;;
+    esac
+    
     tar xjf php-${PHP_VERSION}.tar.bz2
     cd php-${PHP_VERSION}