Fix deprecation warnings thrown when used with PHP 8.4 (#32)

* Drop support for PHP older than 7.1

* Add PHP 8.4 to php workflow

* Fix PHP 8.4 deprecation warning by making nullable all vars with null default value

.github/workflows/php.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         operating-system: ['ubuntu-latest', 'macos-latest']
-        php-versions: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3']
+        php-versions: ['7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
         phpunit-versions: ['latest']
 
     steps:

composer.json

@@ -17,7 +17,7 @@
         }
     ],
     "require": {
-        "php": "~5.6|~7.0|~8.0",
+        "php": "~7.1|~8.0",
         "paragonie/random_compat": ">=2.0"
     },
     "require-dev": {

src/Client.php

@@ -34,9 +34,9 @@ class Client
      *
      * @codeCoverageIgnore
      * @param integer $size
-     * @param GeneratorInterface $generator
+     * @param GeneratorInterface|null $generator
      */
-    public function __construct($size = 21, GeneratorInterface $generator = null)
+    public function __construct($size = 21, ?GeneratorInterface $generator = null)
     {
         $this->size = $size > 0 ? $size : 21;
         $this->generator = $generator ?: new Generator();
@@ -67,12 +67,12 @@ public function generateId($size = 0, $mode = self::MODE_NORMAL)
      * you have been implements your custom GeneratorInterface as correctly.
      * Otherwise use the build-in default random bytes generator
      *
-     * @param GeneratorInterface $generator
+     * @param GeneratorInterface|null $generator
      * @param integer $size
      * @param string $alphabet default CoreInterface::SAFE_SYMBOLS
      * @return string
      */
-    public function formattedId($alphabet, $size = 0, GeneratorInterface $generator = null)
+    public function formattedId($alphabet, $size = 0, ?GeneratorInterface $generator = null)
     {
         $alphabet = $alphabet ?: CoreInterface::SAFE_SYMBOLS;
         $size = $size > 0 ? $size : $this->size;
@@ -86,12 +86,12 @@ public function formattedId($alphabet, $size = 0, GeneratorInterface $generator
      *
      * @param string $alphabet
      * @param integer $size
-     * @param GeneratorInterface $generator
+     * @param GeneratorInterface|null $generator
      *
      * @return string
      * @since 1.0.0
      */
-    public function formatedId($alphabet, $size = 0, GeneratorInterface $generator = null)
+    public function formatedId($alphabet, $size = 0, ?GeneratorInterface $generator = null)
     {
         $size = $size > 0 ? $size : $this->size;