L2SS-951: Disable site-packages and install pytango in tox

tangostationcontrol/requirements.txt

@@ -3,6 +3,8 @@
 # integration process, which may cause wedges in the gate later.
 
 lofar-station-client@git+https://git.astron.nl/lofar2.0/lofar-station-client@0.6.0
+numpy
+mock
 asyncua >= 0.9.90 # LGPLv3
 PyMySQL[rsa] >= 1.0.2 # MIT
 psycopg2-binary >= 2.9.2 # LGPL

tangostationcontrol/tox.ini

@@ -14,7 +14,7 @@ usedevelop = True
 ; installing this package is non-trivial. The solution is to prevent calling
 ; binaries directly and utilizing python and tox variables to resolve the
 ; requested module.
-sitepackages = True
+; sitepackages = True
 install_command = {envbindir}/pip3 install {opts} {packages}
 passenv = HOME
 setenv =
@@ -26,6 +26,7 @@ deps =
     -r{toxinidir}/test-requirements.txt
 commands_pre =
     {envpython} --version
+    pip install --no-cache pytango
 commands =
     {envpython} -m stestr --version
     {envpython} -m stestr run {posargs}