grafana: set cookie SameSite to strict

roles/grafana/templates/grafana.ini.j2

@@ -214,7 +214,7 @@ secret_key = {{ vault_grafana_secret_key }}
 cookie_secure = true
 
 # set cookie SameSite attribute. defaults to `lax`. can be set to "lax", "strict", "none" and "disabled"
-;cookie_samesite = lax
+cookie_samesite = strict
 
 # set to true if you want to allow browsers to render Grafana in a <frame>, <iframe>, <embed> or <object>. default is false.
 ;allow_embedding = false