Fix request.fixturenames to return fixtures created dynamically

Fix #3057

testing/example_scripts/fixtures/test_getfixturevalue_dynamic.py

@@ -0,0 +1,20 @@
+import pytest
+
+
+@pytest.fixture
+def dynamic():
+    pass
+
+
+@pytest.fixture
+def a(request):
+    request.getfixturevalue("dynamic")
+
+
+@pytest.fixture
+def b(a):
+    pass
+
+
+def test(b, request):
+    assert request.fixturenames == ["b", "request", "a", "dynamic"]