systemvm/test: fix sys.path

```
$ bash runtests.sh
/usr/bin/python
Python 3.10.12
Running pycodestyle to check systemvm/python code for errors
Running pylint to check systemvm/python code for errors
Python 3.10.12
pylint 2.12.2
astroid 2.9.3
Python 3.10.12 (main, Nov 20 2023, 15:14:05) [GCC 11.4.0]

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

Running systemvm/python unit tests
....Device "eth0" does not exist.
.....................
----------------------------------------------------------------------
Ran 25 tests in 0.008s

OK
```

systemvm/test/__init__.py

@@ -0,0 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import os
+import sys
+sys.path.append(os.path.join(os.path.dirname(__file__), "..", "debian/opt/cloud/bin"))

systemvm/test/runtests.sh

@@ -45,5 +45,5 @@ then
 fi
 
 echo "Running systemvm/python unit tests"
-nosetests2.7 .
+nosetests3 .
 exit $?