osbuild: add "mypy-strict" check

tox.ini

@@ -7,7 +7,7 @@ env_list =
 labels =
     test = py{36,37,38,39,310,311}
     lint = ruff, isort, autopep8, pylint
-    type = mypy
+    type = mypy,mypy-strict
 
 [testenv]
 description = "run osbuild unit tests"
@@ -26,6 +26,7 @@ deps =
 setenv =
     LINTABLES = osbuild/ assemblers/* devices/* inputs/* mounts/* runners/* sources/* stages/*.* stages/test/*.py test/ tools/
     TYPEABLES = osbuild
+    TYPEABLES_STRICT = ./osbuild/main_cli.py
 
 passenv =
     TEST_CATEGORY
@@ -71,3 +72,10 @@ deps =
 
 commands =
     bash -c 'python -m mypy {env:TYPEABLES}'
+
+[testenv:mypy-strict]
+deps =
+    mypy==1.2.0
+
+commands =
+    bash -c 'python -m mypy --follow-imports=skip --disallow-untyped-calls --disallow-untyped-defs --disallow-incomplete-defs {env:TYPEABLES_STRICT}'