feature: install gh cli if not present (#39)

* feature: added a check if the gh cli binary needs to be installed

* enhancement: added the dependency check

action.yml

@@ -58,6 +58,10 @@ branding:
 runs:
   using: "composite"
   steps:
+    - name: "Install the gh cli tool if not installed"
+      shell: bash
+      run: ./deps.sh
+
     - name: "Error missing auth conf"
       if: inputs.gh_app_secret_key == '' && inputs.gh_app_ID == '' && inputs.gh_token == ''
       shell: bash

deps.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+# check if gh binary is available
+if [ -x "$(command -v gh)" ]; then
+    echo 'gh cli is installed.'
+    exit 0
+fi
+
+version=${GH_CLI_VERSION:-2.8.0}
+echo "Installing gh cli in version: $version"
+
+wget https://github.com/cli/cli/releases/download/v${version}/gh_${version}_linux_amd64.tar.gz
+tar -xvf gh_${version}_linux_amd64.tar.gz
+sudo cp $(pwd)/gh_${version}_linux_amd64/bin/gh /usr/local/bin/