pin pytest version to Debian's development distribution version

Author: mr-c

setup.py

@@ -121,7 +121,7 @@
     setup_requires=PYTEST_RUNNER,
     test_suite="tests",
     tests_require=[
-        "pytest < 7",
+        "pytest == 6.0.2",
         "mock >= 2.0.0",
         "pytest-mock >= 1.10.0",
         "arcp >= 0.2.0",

test-requirements.txt

@@ -1,4 +1,4 @@
-pytest < 7
+pytest == 6.0.2
 mock >= 2.0.0
 pytest-mock >= 1.10.0
 pytest-cov