Task: Add collaborators to GitHub from Google Sheet

n8n workflow JSON:
{"id":"6","name":"Add Collaborators to GitHub from Google Sheet","nodes":[{"name":"On clicking 'execute'","type":"n8n-nodes-base.manualTrigger","position":[250,300],"parameters":{},"typeVersion":1},{"name":"HTTP Request","type":"n8n-nodes-base.httpRequest","position":[650,300],"parameters":{"url":"=https://api.github.com/repos/<USERNAME>/<REPO-NAME>/collaborators/{{$node[\"Google Sheets\"].json[\"Username\"]}}","options":{},"requestMethod":"PUT","headerParametersUi":{"parameter":[{"name":"User-Agent","value":"n8n"},{"name":"Authorization","value":"token <GITHUB-ACCESS-TOKEN>"}]}},"typeVersion":1},{"name":"Google Sheets","type":"n8n-nodes-base.googleSheets","position":[450,300],"parameters":{"range":"A:A","options":{},"sheetId":"YOUR-GOOGLE-SHEET-ID","authentication":"oAuth2"},"credentials":{"googleSheetsOAuth2Api":"google-sheet"},"typeVersion":1}],"active":false,"settings":{},"connections":{"Google Sheets":{"main":[[{"node":"HTTP Request","type":"main","index":0}]]},"On clicking 'execute'":{"main":[[{"node":"Google Sheets","type":"main","index":0}]]}}}