Convert backslashes to slashes before string replace

(closes #1577)

They will be backslashes when the script runs on Windows.
The node:fs functions can handle either, but string.replace needs them consistent.

scripts/build_data.js

@@ -124,7 +124,7 @@ function buildDataAsync() {
 
       // copy `data/` files to `dist/data/` and stamp with metadata
       for (const sourceFile of globSync('data/**/*.json')) {
-        const destinationFile = sourceFile.replace('data/', 'dist/data/');
+        const destinationFile = sourceFile.replace(/\\/g, '/').replace('data/', 'dist/data/');
         copyToDistSync(sourceFile, destinationFile);
       }