Fix coverage reporting.

The previous commit added reporting on coverage in the tests/ directory,
 but accidentally excluded the src/ directory. This ensures the coverage
  report includes both.

Author: ubernostrum

noxfile.py

@@ -78,10 +78,6 @@ def tests_with_coverage(session: nox.Session) -> None:
         "-Im",
         "coverage",
         "run",
-        "--source",
-        PACKAGE_NAME,
-        "--source",
-        "tests/",
         "-m",
         "pytest",
         "-m",

pyproject.toml

@@ -67,7 +67,7 @@ fail_under = 100
 [tool.coverage.run]
 branch = true
 parallel = true
-source = ["akismet"]
+source = ["akismet", "tests"]
 
 [tool.interrogate]
 fail-under = 100