cephadm: add python-common/ceph to MYPYPATH and pytest PYTHONPATH

Otherwise the unit tests will fail trying to import from here.

Signed-off-by: Adam King <adking@redhat.com>

src/cephadm/tox.ini

@@ -24,6 +24,10 @@ exclude =
 statistics = True
 
 [testenv]
+setenv =
+    PYTHONPATH = $PYTHONPATH:..:{toxinidir}/../python-common
+passenv =
+    PYTHONPATH
 skip_install=true
 deps =
   -rzipapp-reqs.txt
@@ -35,6 +39,10 @@ deps =
 commands=pytest {posargs}
 
 [testenv:mypy]
+setenv =
+    MYPYPATH = {toxinidir}/..:{toxinidir}/../python-common
+passenv =
+    MYPYPATH
 deps =
     mypy
     types-PyYAML