fix Windows bug hopefully (https://forum.image.sc/t/bigstitcher-zarr-…

…multi-resolution-pyramid-windows-10/101553)

src/main/java/net/preibisch/mvrecon/process/export/ExportN5Api.java

@@ -243,10 +243,13 @@ else if ( storageType == StorageFormat.N5 || storageType == StorageFormat.ZARR )
 			// this is the relative path to the dataset inside the Zarr/N5/HDF5 container, thus using File here seems fine
 			final String dataset = new File( new File( baseDataset , title ).toString(), datasetExtension ).toString();
 
+			// e.g. in Windows this will change it to '\s0'
+			final String datasetExtensionOS = new File( datasetExtension ).toString(); 
+
 			// setup multi-resolution pyramid
 			mrInfo = N5ApiTools.setupMultiResolutionPyramid(
 					driverVolumeWriter,
-					(level) -> dataset.substring(0, dataset.lastIndexOf( datasetExtension ) ) + "/s" + level,
+					(level) -> new File( dataset.substring(0, dataset.lastIndexOf( datasetExtensionOS ) ) + "/s" + level ).toString(),
 					dataType,
 					bb.dimensionsAsLongArray(),
 					compression,