add redis role for ensuring redis is installed from distro packages

This is a requirement for a new netbox role.

roles/redis/README.md

@@ -0,0 +1,15 @@
+# Role `redis`
+
+Ensures `redis` is installed by installing the distributions package.
+
+## Supported Distributions
+
+Should work on Debian-based distributions.
+
+## Required Arguments
+
+None.
+
+## Optional Arguments
+
+None.

roles/redis/tasks/main.yaml

@@ -0,0 +1,5 @@
+- name: Ensure redis is installed
+  ansible.builtin.apt:
+    name:
+      - redis
+  become: true