Use link as part of attachment in slack payload

Question

I am using this action to post a message to a slack channel through a Github Actions workflow.

I am constructing the payload as follows

      - name: set slack payload
        uses: actions/github-script
        with:
          script: |
            const payload = {
              "text": "Some text",
              "username": "Some username",
              "icon_url": "https://www.ecample.com/icon.png",
              "attachments": [
                {
                  "mrkdwn_in": ["text"],
                  "color": "'#ffffff'",
                  "fields": [
                    {
                      "title": "A title",
                      "value": "some text",
                      "short": true
                    },
                    {
                      "title": "Mention",
                      "value": "<@username> hello",
                      "short": true
                    },
                  ]
                }
              ]
            }
            core.setOutput('payload', payload)

I am trying to add a link element as follows

      - name: set slack payload
        uses: actions/github-script
        with:
          script: |
            const payload = {
              "text": "Some text",
              "username": "Some username",
              "icon_url": "https://www.ecample.com/icon.png",
              "attachments": [
                {
                  "mrkdwn_in": ["text"],
                  "color": "'#ffffff'",
                  "fields": [
                    {
                      "title": "A title",
                      "value": "some text",
                      "short": true
                    },
                    {
                      type: "link",
                      "text": "Something",
                      "url": "https://example.com",
                      "short": true
                    },
                  ]
                }
              ]
            }
            core.setOutput('payload', payload)

The message is composed and posted to slack all right but the specific block with the url is totally missing.

Any ideas?