use cloudalchemybot when accessing github api (cloudalchemy#120)

This will cause to access github API as authenticated cloudalchemybot user (when there is GH_TOKEN variable set) or unauthenticated (when there is no GH_TOKEN var)

Resolves cloudalchemy#115

tasks/preflight.yml

@@ -36,14 +36,17 @@
   with_dict: "{{ prometheus_targets }}"
 
 - block:
-    - name: get latest release
+    - name: Get latest release
       uri:
         url: "https://api.github.com/repos/prometheus/prometheus/releases/latest"
         method: GET
         return_content: true
         status_code: 200
         body_format: json
         validate_certs: false
+        user: "{{ lookup('env', 'GH_USER') | default(omit) }}"
+        password: "{{ lookup('env', 'GH_TOKEN') | default(omit) }}"
+      no_log: true
       register: _latest_release
       until: _latest_release.status == 200
       retries: 5