feature #165 [1.x] UriSigner to become internal in 2.x

* [1.x] UriSigner to become internal in 2.x

* start an upgrade guide for 2.0

UPGRADING.md

@@ -0,0 +1,6 @@
+# Upgrade from 1.x to 2.0
+
+## UriSignerFactory
+
+- The `UriSignerFactory` became `@internal` & `@final`. This class should not be
+used.

src/Factory/UriSignerFactory.php

@@ -15,16 +15,20 @@
 /**
  * @author Victor Bocharsky <[email protected]>
  * @author Ryan Weaver      <[email protected]>
+ *
+ * Will become final && internal and ultimately removed in v2.0.
+ *
+ * @internal
+ *
+ * @final
  */
 class UriSignerFactory
 {
-    private $secret;
-    private $parameter;
-
-    public function __construct(string $secret, string $parameter = '_hash')
-    {
-        $this->secret = $secret;
-        $this->parameter = $parameter;
+    public function __construct(
+        #[\SensitiveParameter]
+        private string $secret,
+        private string $parameter = '_hash'
+    ) {
     }
 
     /**