ci: test PHP 8.2-8.4 against Cacti and add ondrej PPA for apache mod

Cacti core now requires PHP >= 8.2, so the 8.1 integration job fails the
composer platform check; Ubuntu Noble also lacks libapache2-mod-php for
non-native versions without the ondrej PPA.

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

Author: somethingwithproof

.github/workflows/plugin-ci-workflow.yml

@@ -38,7 +38,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['8.1', '8.2', '8.3', '8.4']
+        php: ['8.2', '8.3', '8.4']
         os: [ubuntu-latest]
 
     services:
@@ -82,7 +82,9 @@ jobs:
       run: php -v
 
     - name: Run apt-get update
-      run: sudo apt-get update
+      run: |
+        sudo add-apt-repository -y ppa:ondrej/php
+        sudo apt-get update
     
     - name: Install System Dependencies
       run: sudo apt-get install -y apache2 snmp snmpd rrdtool fping