Updated files with 'repo_helper'. (#36)

Co-authored-by: repo-helper[bot] <74742576+repo-helper[bot]@users.noreply.github.com>

Author: repo-helper[bot]

.isort.cfg

@@ -54,6 +54,7 @@ known_third_party =
     sdjson
     shippinglabel
     southwark
+    toml
     tomlkit
     tox
     tox_battery

tox.ini

@@ -119,6 +119,7 @@ commands =
 plugins = coverage_pyver_pragma
 
 [coverage:report]
+fail_under = 80
 exclude_lines =
     raise AssertionError
     raise NotImplementedError
@@ -127,7 +128,7 @@ exclude_lines =
     if TYPE_CHECKING:
     if typing.TYPE_CHECKING:
     if __name__ == .__main__.:
-    :[\n\s]*\.\.\.
+    :[\n\s]*\.\.\.$
 omit = **/*._py
 
 [check-wheel-contents]