[BC Break] Make data providers for abstract test cases static

Author: OskarStark

Tests/SmscTransportFactoryTest.php

@@ -25,26 +25,26 @@ public function createFactory(): TransportFactoryInterface
         return new SmscTransportFactory();
     }
 
-    public function createProvider(): iterable
+    public static function createProvider(): iterable
     {
         yield [
             'smsc://host.test?from=MyApp',
             'smsc://login:[email protected]?from=MyApp',
         ];
     }
 
-    public function supportsProvider(): iterable
+    public static function supportsProvider(): iterable
     {
         yield [true, 'smsc://login:password@default?from=MyApp'];
         yield [false, 'somethingElse://login:password@default?from=MyApp'];
     }
 
-    public function missingRequiredOptionProvider(): iterable
+    public static function missingRequiredOptionProvider(): iterable
     {
         yield 'missing option: from' => ['smsc://login:password@default'];
     }
 
-    public function unsupportedSchemeProvider(): iterable
+    public static function unsupportedSchemeProvider(): iterable
     {
         yield ['somethingElse://login:password@default?from=MyApp'];
         yield ['somethingElse://login:password@default']; // missing "from" option