tests: add a dummy value for 'dev' release

Functional tests are broken when testing against 'dev' release (ceph).
Adding a dummy value here will make it possible to run ceph-ansible CI
against dev ceph release.

Typical error:

```
>       if request.node.get_marker("from_luminous") and ceph_release_num[ceph_stable_release] < ceph_release_num['luminous']:
E       KeyError: 'dev'
```

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit fd1487d93f21b609a637053f5b33cd2a4e408d00)

group_vars/all.yml.sample

@@ -28,6 +28,7 @@ dummy:
 #  luminous: 12
 #  mimic: 13
 #  nautilus: 14
+#  dev: 99
 
 # Directory to fetch cluster fsid, keys etc...
 #fetch_directory: fetch/

group_vars/rhcs.yml.sample

@@ -28,6 +28,7 @@ dummy:
 #  luminous: 12
 #  mimic: 13
 #  nautilus: 14
+#  dev: 99
 
 # Directory to fetch cluster fsid, keys etc...
 fetch_directory: ~/ceph-ansible-keys

roles/ceph-defaults/defaults/main.yml

@@ -20,6 +20,7 @@ ceph_release_num:
   luminous: 12
   mimic: 13
   nautilus: 14
+  dev: 99
 
 # Directory to fetch cluster fsid, keys etc...
 fetch_directory: fetch/

tests/conftest.py

@@ -25,7 +25,8 @@ def node(host, request):
       'jewel': 10,
       'kraken': 11,
       'luminous': 12,
-      'mimic': 13
+      'mimic': 13,
+      'dev': 99
     }
     if not request.node.get_marker(node_type) and not request.node.get_marker('all'):
         pytest.skip("Not a valid test for node type: %s" % node_type)