Fix array access issues in php 8.x

src/Authentication/ApiKey/ApiKey.php

@@ -179,6 +179,7 @@ private function format_date( int $timestamp, string $format = null ): string {
 		return $datetime->format( $format );
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Whether a field exists.
 	 *
@@ -191,6 +192,7 @@ public function offsetExists( $name ): bool {
 		return isset( $this->data[ $name ] );
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Retrieve a field value.
 	 *
@@ -213,6 +215,7 @@ public function offsetGet( $name ) {
 		return null;
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Set a field value.
 	 *
@@ -227,6 +230,7 @@ public function offsetSet( $name, $value ) {
 		}
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Remove a field.
 	 *

src/PackageType/BasePackage.php

@@ -388,6 +388,7 @@ public function is_update_available(): bool {
 		return $this->is_installed() && version_compare( $this->get_installed_version(), $this->get_latest_version(), '<' );
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Whether a property exists.
 	 *
@@ -402,6 +403,7 @@ public function offsetExists( $name ): bool {
 		return method_exists( $this, "get_{$name}" );
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Retrieve a property value.
 	 *
@@ -420,6 +422,7 @@ public function offsetGet( $name ) {
 		return $this->$method();
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Set a property value.
 	 *
@@ -432,6 +435,7 @@ public function offsetSet( $name, $value ) {
 		// Prevent properties from being modified.
 	}
 
+	#[\ReturnTypeWillChange]
 	/**
 	 * Unset a property.
 	 *