chore: Add Dependabot config and GitHub Actions for PHP CI

This commit introduces a Dependabot configuration for daily Composer updates and a GitHub Actions workflow for PHP dependency management and validation. It also updates `composer.json` to require PHP 8.3+, bumps PHPUnit to 12.0.10, and adjusts the README to reflect the new PHP version requirement.

Author: efebagri

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: composer
+    directory: /
+    schedule:
+      interval: daily

.github/workflows/php.yml

@@ -0,0 +1,32 @@
+name: PHP Composer
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Update Composer dependencies
+        run: composer update --no-interaction --no-progress
+
+      - name: Validate composer.json and composer.lock
+        run: composer validate --strict
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v3
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-
+
+      - name: Install dependencies
+        run: composer install --prefer-dist --no-progress

README.md

@@ -6,7 +6,7 @@
 
 # Getting Started
 ### Requirements
-* [**PHP 7.4+**](https://www.php.net/downloads.php)
+* [**PHP 8.3+**](https://www.php.net/downloads.php)
 * Extensions: [Composer](https://getcomposer.org/), [PHP-JSON](https://www.php.net/manual/en/book.json.php)
 
 # ⚒️ Install

composer.json

@@ -12,7 +12,7 @@
   "license": "MIT",
   "authors": [
     {
-      "name": "Efe Bagri",
+      "name": "Efe Bağrı",
       "email": "composer@exbil.net",
       "homepage": "https://www.exbil.net/"
     }
@@ -22,15 +22,15 @@
     "source": "https://github.com/exbil/lexoffice-php-api"
   },
   "require": {
-    "php": "^7.4 | ^8",
+    "php": ">=8.3",
     "ext-json": "*",
     "ext-curl": "*",
     "guzzlehttp/guzzle": "^6.2 | ^7.0",
     "psr/cache": "^1.0 | ^2.0 | ^3.0"
   },
   "require-dev": {
     "fzaninotto/faker": "^1.9.1",
-    "phpunit/phpunit": "^9.0",
+    "phpunit/phpunit": "^12.0.10",
     "symfony/cache": "^5.1"
   },
   "autoload": {