Explicitly declare allowPrivilegeEscalation to false

Although containers that do not run as privileged already have this set to false by kubernetes
Kubespace [asks us](https://hub.armo.cloud/docs/c-0016) to explicitly declare it to false where not needed.

Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>

manifests/grafana-deployment.yaml

@@ -45,6 +45,8 @@ spec:
           requests:
             cpu: 100m
             memory: 100Mi
+        securityContext:
+          allowPrivilegeEscalation: false
         volumeMounts:
         - mountPath: /var/lib/grafana
           name: grafana-storage