Fix duplicate env key in Install Copilot CLI step

Merge GITHUB_TOKEN into the single env block to fix the 'env is already
defined' validation error in GitHub Actions.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

action.yml

@@ -27,9 +27,8 @@ runs:
       env:
         VERSION: ${{ inputs.version }}
         PREFIX: ${{ runner.tool_cache }}/copilot
-      run: curl -fsSL https://gh.io/copilot-install | bash
-      env:
         GITHUB_TOKEN: ${{ inputs.github-token }}
+      run: curl -fsSL https://gh.io/copilot-install | bash
 
     - name: Add to PATH
       shell: bash