Add an example that pulls in the sb fixture during a test

Author: mdmintz

examples/test_request_sb_fixture.py

@@ -0,0 +1,8 @@
+def test_request_sb_fixture(request):
+    sb = request.getfixturevalue('sb')
+    sb.open("https://seleniumbase.io/demo_page")
+    sb.assert_text("SeleniumBase", "#myForm h2")
+    sb.assert_element("input#myTextInput")
+    sb.type("#myTextarea", "This is me")
+    sb.click("#myButton")
+    sb.tearDown()