Task: Send an email using Mailgun

n8n workflow JSON:
{"nodes":[{"name":"On clicking 'execute'","type":"n8n-nodes-base.manualTrigger","position":[250,300],"parameters":{},"typeVersion":1},{"name":"Mailgun","type":"n8n-nodes-base.mailgun","position":[450,300],"parameters":{"text":"This is a test message ","subject":"This is a Subject","toEmail":"user2@example.com","fromEmail":"user@example.com"},"credentials":{"mailgunApi":"mailgun-creds"},"typeVersion":1}],"connections":{"On clicking 'execute'":{"main":[[{"node":"Mailgun","type":"main","index":0}]]}}}