update mdviewer test to click on https link

Author: Aearsears

tests/test_markdownviewer.py

@@ -12,6 +12,7 @@
 TEST_MARKDOWN = """\
 * [First]({{file}}#first)
 * [Second](#second)
+* [GitHub](https://github.com/textualize/textual/)
 
 # First
 
@@ -37,7 +38,7 @@ async def on_mount(self) -> None:
         await self.query_one(MarkdownViewer).go(self.markdown_file)
 
 
-@pytest.mark.parametrize("link", [0, 1])
+@pytest.mark.parametrize("link", [0, 1, 2])
 async def test_markdown_file_viewer_anchor_link(tmp_path, link: int) -> None:
     """Test https://github.com/Textualize/textual/issues/3094"""
     async with MarkdownFileViewerApp(Path(tmp_path) / "test.md").run_test() as pilot:
@@ -59,7 +60,7 @@ async def on_mount(self) -> None:
         self.query_one(MarkdownViewer).show_table_of_contents = False
 
 
-@pytest.mark.parametrize("link", [0, 1])
+@pytest.mark.parametrize("link", [0, 1, 2])
 async def test_markdown_string_viewer_anchor_link(link: int) -> None:
     """Test https://github.com/Textualize/textual/issues/3094