upgrade to ansible 2.4

tasks/main.yml

@@ -1,13 +1,13 @@
 ---
 
-- include: directory.yml
+- import_tasks: directory.yml
   when: certificate_directory is defined
 
 - name: setup
-  include: setup_{{ansible_os_family}}.yml
+  include_tasks: setup_{{ansible_os_family}}.yml
 
 - name: method
-  include: "provider-{{ certificate_provider }}.yml"
+  include_tasks: "provider-{{ certificate_provider }}.yml"
 
 # - name: info
 #   command: openssl x509 -text -noout

tasks/provider-ca.yml

@@ -1,7 +1,7 @@
 ---
 
-- include: key.yml
-- include: csr.yml
+- include_tasks: key.yml
+- include_tasks: csr.yml
 
 - name: certificate host_files directory
   local_action: file