Fixing jobs with tox4

Adding scripts to allowlist_externals
Adding explicitly requirements.txt to the deps list
Removing basepython and skipsdist

Change-Id: I3ef4f7f5d03c84b9091dd97a272f64da680c6e2d

tox.ini

@@ -1,11 +1,9 @@
 [tox]
 minversion = 3.18.0
 envlist = py3,pep8
-skipsdist = True
 ignore_basepython_conflict = True
 
 [testenv]
-basepython = python3
 usedevelop = True
 allowlist_externals =
     find
@@ -16,6 +14,7 @@ setenv =
    PYTHONWARNINGS=default::DeprecationWarning
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+    -r{toxinidir}/requirements.txt
     -r{toxinidir}/test-requirements.txt
 commands =
     find . -type f -name "*.pyc" -delete
@@ -34,6 +33,7 @@ allowlist_externals =
   sh
   find
   bash
+  {toxinidir}/tools/coding-checks.sh
 
 [testenv:venv]
 commands = {posargs}