Sort commits using isort

Also added lint test to ensure they stay sorted.

tests/test_black.py

@@ -1,20 +0,0 @@
-from click.testing import CliRunner
-from pathlib import Path
-import pytest
-import sys
-
-code_root = Path(__file__).parent.parent
-
-
-@pytest.mark.skipif(
-    sys.version_info[:2] < (3, 6), reason="Black requires Python 3.6 or later"
-)
-def test_black():
-    # Do not import at top of module because Python 3.5 will not have it installed
-    import black
-
-    runner = CliRunner()
-    result = runner.invoke(
-        black.main, [str(code_root / "tests"), str(code_root / "datasette"), "--check"]
-    )
-    assert result.exit_code == 0, result.output