fix: redis clients unable to perform write commands (#89)

sets redis securityContext.fsGroup

Fixes the following error (redis clients stack tracing; pods
loopcrashing)

MISCONF Redis is configured to save RDB snapshots, but it's currently
unable to persist to disk. Commands that may modify the data set are
disabled, because this instance is configured to report errors during
writes if RDB snapshotting fails (stop-writes-on-bgsave-error option).
Please check the Redis logs for details about the RDB error.
(redis://redis:6379)

Author: archf

charts/opslevel/values.yaml

@@ -217,7 +217,8 @@ redis:
     create: true
     name: redis
     annotations: {}
-  securityContext: {}
+  securityContext:
+    fsGroup: 999
   #    fsGroupChangePolicy: Always
   #    supplementalGroups: []
   #    sysctls: []