Update galaxy.yml, make ansible-lint happier

roles/gitea/tasks/main.yml

@@ -4,16 +4,16 @@
   group:
     name: git
     gid: 2132
-    system: yes
+    system: true
 
 - name: Create git user on host for gitea ssh
   user:
     name: git
     uid: 2132
     group: git
-    system: yes
+    system: true
     home: /var/lib/gitea
-    generate_ssh_key: yes
+    generate_ssh_key: true
   register: git_user
 
 - name: Add git user's own ssh key to its authorized keys