Add support for proxy networks & cleanup playbook vars

roles/gh/tasks/Debian.yaml

@@ -15,6 +15,7 @@
     url: https://cli.github.com/packages/githubcli-archive-keyring.gpg
     dest: /usr/share/keyrings/githubcli-archive-keyring.gpg
     mode: 0644
+  environment: '{{proxy_environment}}'
 
 - name: add apt repository list
   become: true

roles/gh/tasks/RedHat.yaml

@@ -4,6 +4,7 @@
   get_url:
     url: https://cli.github.com/packages/rpm/gh-cli.repo
     dest: /etc/yum.repos.d/gh-cli.repo
+  environment: '{{proxy_environment}}'
 
 - name: install dnf package
   become: true