Update fixture.rst

Remove yet another not needed `request` argument in fixture definition.

doc/en/fixture.rst

@@ -253,7 +253,7 @@ the code after the *yield* statement serves as the teardown code:
     import pytest
 
     @pytest.fixture(scope="module")
-    def smtp(request):
+    def smtp():
         smtp = smtplib.SMTP("smtp.gmail.com")
         yield smtp  # provide the fixture value
         print("teardown smtp")