refactor: use ansible.posix 2.1.X for EL7 compatibility

The recently released ansible.posix 2.2.0 does not work on EL7.
Pin the version of ansible.posix to 2.1.X.

NOTE: Even though this role might not support EL7, this update
is applied to all system roles for consistency.

Signed-off-by: Rich Megginson <rmeggins@redhat.com>

Author: richm

meta/collection-requirements.yml

@@ -2,3 +2,4 @@
 ---
 collections:
   - name: ansible.posix
+    version: <2.2.0