Sets always_run on second pip version check

Necessary to support --check mode when setting pip_version to "latest".

tasks/main.yml

@@ -28,6 +28,7 @@
   shell: "{{ pip }} --version | awk '{print $2}'"
   register: pip_installed_version
   changed_when: false
+  always_run: true # for check mode
   when: pip_version != None or pip_version != "LATEST"
 
 - name: Install required version of pip.