What’s this strange script doing in my GitHub repo?

I was going through one of my GitHub repositories when I stumbled upon this script at the top of my index.html file, which I definitely don't remember adding:
```javascript
<script type="text/javascript">
var gk_isXlsx = false;
var gk_xlsxFileLookup = {};
var gk_fileData = {};
function filledCell(cell) {
return cell !== '' && cell != null;
}
function loadFileData(filename) {
if (gk_isXlsx && gk_xlsxFileLookup[filename]) {
try {
var workbook = XLSX.read(gk_fileData[filename], { type: 'base64' });
var firstSheetName = workbook.SheetNames[0];
var worksheet = workbook.Sheets[firstSheetName];

// Convert sheet to JSON to filter blank rows
var jsonData = XLSX.utils.sheet_to_json(worksheet, { header: 1, blankrows: false, defval: '' });
// Filter out blank rows
var filteredData = jsonData.filter(row => row.some(filledCell));

// Heuristic to find the header row
var headerRowIndex = filteredData.findIndex((row, index) =>
row.filter(filledCell).length >= filteredData[index + 1]?.filter(filledCell).length
);
// Fallback
if (headerRowIndex === -1 || headerRowIndex > 25) {
headerRowIndex = 0;
}

// Convert filtered JSON back to CSV
var csv = XLSX.utils.aoa_to_sheet(filteredData.slice(headerRowIndex));
csv = XLSX.utils.sheet_to_csv(csv, { header: 1 });
return csv;
} catch (e) {
console.error(e);
return "";
}
}
return gk_fileData[filename] || "";
}
</script>
```

The only file I have in this repo is index.html, and there are no GitHub Actions implemented. After searching online, I discovered that this exact script appears in several places:
- [Kaggle dataset](https://www.kaggle.com/datasets/waleed1980/global-pharmacy-bi-bloom-dataset/data)
- [Domoticz forum](https://forum.domoticz.com/viewtopic.php?p=326841&sid=50d57b4e00bf7ab23dc6e802b5c001dd#p326841)
- [CodePen](https://codepen.io/Dipin-Kakkar/pen/xbGwoXa)

So, does anyone know what this script is or how it ended up in my repository? I'm aware that it's related to converting .xlsx files to .csv via JSON.