pybind/mgr: attempt to fix mypy importing from python-common

For some reason mypy on python 3.12 can no longer automatically find
imports from python-common. Help it out by expanding the MYPYPATH
value for the tox.ini.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

src/pybind/mgr/tox.ini

@@ -69,7 +69,7 @@ commands =
 
 [testenv:{,py37-,py38-,py39-,py310-}mypy]
 setenv =
-    MYPYPATH = {toxinidir}/..
+    MYPYPATH = {toxinidir}/..:{toxinidir}/../../python-common
 passenv =
     MYPYPATH
 deps =