Spotify PKCE support

Author: codemasher

README.md

@@ -140,7 +140,7 @@ Note: check the [releases](https://github.com/chillerlan/php-oauth/releases) for
 | [Reddit](https://www.reddit.com/dev/api) | [link](https://www.reddit.com/prefs/apps/) | [link](https://www.reddit.com/settings/privacy) | 2 | ✓ | ✓ |  | ✓ | ✓ | ✓ |
 | [Slack](https://api.slack.com) | [link](https://api.slack.com/apps) | [link](https://slack.com/apps/manage) | 2 | ✓ | ✓ |  |  |  |  |
 | [SoundCloud](https://developers.soundcloud.com/) | [link](https://soundcloud.com/you/apps) | [link](https://soundcloud.com/settings/connections) | 2 | ✓ |  |  | ✓ | ✓ |  |
-| [Spotify](https://developer.spotify.com/documentation/web-api/) | [link](https://developer.spotify.com/dashboard) | [link](https://www.spotify.com/account/apps/) | 2 | ✓ | ✓ |  | ✓ | ✓ |  |
+| [Spotify](https://developer.spotify.com/documentation/web-api/) | [link](https://developer.spotify.com/dashboard) | [link](https://www.spotify.com/account/apps/) | 2 | ✓ | ✓ | ✓ | ✓ | ✓ |  |
 | [Steam](https://developer.valvesoftware.com/wiki/Steam_Web_API) | [link](https://steamcommunity.com/dev/apikey) |  | - | ✓ |  |  |  |  |  |
 | [Stripe](https://stripe.com/docs/api) | [link](https://dashboard.stripe.com/apikeys) | [link](https://dashboard.stripe.com/account/applications) | 2 | ✓ | ✓ |  |  | ✓ | ✓ |
 | [Tumblr](https://www.tumblr.com/docs/en/api/v2) | [link](https://www.tumblr.com/oauth/apps) | [link](https://www.tumblr.com/settings/apps) | 1 | ✓ |  |  |  |  |  |

docs/Basics/Overview.md

@@ -75,7 +75,7 @@ fully [PSR-7](https://www.php-fig.org/psr/psr-7/)/[PSR-17](https://www.php-fig.o
 | [Reddit](https://www.reddit.com/dev/api) | [link](https://www.reddit.com/prefs/apps/) | [link](https://www.reddit.com/settings/privacy) | 2 | ✓ | ✓ |  | ✓ | ✓ | ✓ |
 | [Slack](https://api.slack.com) | [link](https://api.slack.com/apps) | [link](https://slack.com/apps/manage) | 2 | ✓ | ✓ |  |  |  |  |
 | [SoundCloud](https://developers.soundcloud.com/) | [link](https://soundcloud.com/you/apps) | [link](https://soundcloud.com/settings/connections) | 2 | ✓ |  |  | ✓ | ✓ |  |
-| [Spotify](https://developer.spotify.com/documentation/web-api/) | [link](https://developer.spotify.com/dashboard) | [link](https://www.spotify.com/account/apps/) | 2 | ✓ | ✓ |  | ✓ | ✓ |  |
+| [Spotify](https://developer.spotify.com/documentation/web-api/) | [link](https://developer.spotify.com/dashboard) | [link](https://www.spotify.com/account/apps/) | 2 | ✓ | ✓ | ✓ | ✓ | ✓ |  |
 | [Steam](https://developer.valvesoftware.com/wiki/Steam_Web_API) | [link](https://steamcommunity.com/dev/apikey) |  | - | ✓ |  |  |  |  |  |
 | [Stripe](https://stripe.com/docs/api) | [link](https://dashboard.stripe.com/apikeys) | [link](https://dashboard.stripe.com/account/applications) | 2 | ✓ | ✓ |  |  | ✓ | ✓ |
 | [Tumblr](https://www.tumblr.com/docs/en/api/v2) | [link](https://www.tumblr.com/oauth/apps) | [link](https://www.tumblr.com/settings/apps) | 1 | ✓ |  |  |  |  |  |

src/Providers/Spotify.php

@@ -13,16 +13,17 @@
 
 namespace chillerlan\OAuth\Providers;
 
-use chillerlan\OAuth\Core\{AuthenticatedUser, ClientCredentials, CSRFToken, OAuth2Provider, TokenRefresh, UserInfo};
+use chillerlan\OAuth\Core\{AuthenticatedUser, ClientCredentials, CSRFToken, OAuth2Provider, PKCE, TokenRefresh, UserInfo};
 
 /**
  * Spotify OAuth2
  *
  * @link https://developer.spotify.com/documentation/web-api
  * @link https://developer.spotify.com/documentation/web-api/tutorials/code-flow
  * @link https://developer.spotify.com/documentation/web-api/tutorials/client-credentials-flow
+ * @link https://developer.spotify.com/documentation/web-api/tutorials/code-pkce-flow
  */
-class Spotify extends OAuth2Provider implements ClientCredentials, CSRFToken, TokenRefresh, UserInfo{
+class Spotify extends OAuth2Provider implements ClientCredentials, CSRFToken, PKCE, TokenRefresh, UserInfo{
 
 	public const IDENTIFIER = 'SPOTIFY';