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

Author: OskarStark

Tests/ClickatellTransportFactoryTest.php

@@ -25,26 +25,26 @@ public function createFactory(): TransportFactoryInterface
         return new ClickatellTransportFactory();
     }
 
-    public function createProvider(): iterable
+    public static function createProvider(): iterable
     {
         yield [
             'clickatell://host.test?from=0611223344',
             'clickatell://authtoken@host.test?from=0611223344',
         ];
     }
 
-    public function supportsProvider(): iterable
+    public static function supportsProvider(): iterable
     {
         yield [true, 'clickatell://authtoken@default?from=0611223344'];
         yield [false, 'somethingElse://authtoken@default?from=0611223344'];
     }
 
-    public function incompleteDsnProvider(): iterable
+    public static function incompleteDsnProvider(): iterable
     {
         yield 'missing auth token' => ['clickatell://host?from=FROM'];
     }
 
-    public function unsupportedSchemeProvider(): iterable
+    public static function unsupportedSchemeProvider(): iterable
     {
         yield ['somethingElse://authtoken@default?from=FROM'];
         yield ['somethingElse://authtoken@default']; // missing "from" option