Fix molecule requirements

There's a pytest-molecule bug around ansible version in the latest
version. Pin it to <1.30 for now.

Additionally move the requirements out of tox.ini into it's own file to
match other repositories.

Change-Id: I516b38fa0766a9aaa15c00495cae4a781b769c4c
Partial-Bug: #1900033

molecule-requirements.txt

@@ -0,0 +1,13 @@
+ansi2html
+ansible>=2.9,<2.10
+docker>=4.0.1
+paramiko>=2.5.0  # LGPL (soft-dependency of docker that enables ssh protocol)
+pytest
+pytest-cov
+pytest-html<=2.0.1  # MPL 2.0
+pytest-molecule<1.3.0
+pytest-xdist
+mock
+molecule>=3.0,<3.1  # MIT
+selinux>=0.2.1  # MIT
+oslotest

tox.ini

@@ -124,18 +124,7 @@ setenv =
     ANSIBLE_CALLBACK_WHITELIST=profile_tasks
     ANSIBLE_SHOW_CUSTOM_STATS=1
 deps =
-    ansi2html  # GPL (soft-dependency of pytest-html)
-    ansible>=2.9
-    docker>=4.0.1
-    mock
-    molecule==3.0a9  # MIT
-    paramiko>=2.5.0  # LGPL (soft-dependency of docker that enables ssh protocol)
-    pytest-cov  # MIT
-    pytest-html<=2.0.1  # MPL 2.0
-    pytest-molecule>=1.2.4  # MIT
-    pytest-xdist
-    selinux>=0.2.1  # MIT
-    oslotest
+  -r {toxinidir}/molecule-requirements.txt
 commands =
     python -m pytest -ra --continue-on-collection-errors -v --color=yes --html={envlogdir}/reports.html --self-contained-html {tty:-s} -k {posargs}