[shotwell] Fix an issue with the WEBP meta-data writer

[Jens Georg <jensgeorg src gnome org>]

commit 57ab1628883e3fde5bb3eafc0197b4e17354d2a6
Author: Jens Georg <mail jensge org>
Date:   Sat Feb 9 16:43:15 2019 +0100

    Fix an issue with the WEBP meta-data writer

 src/photos/WebPSupport.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/photos/WebPSupport.vala b/src/photos/WebPSupport.vala
index 093f196c..2f4723cb 100644
--- a/src/photos/WebPSupport.vala
+++ b/src/photos/WebPSupport.vala
@@ -213,7 +213,7 @@ private class WebpReader : PhotoFileReader {
 
 private class WebpMetadataWriter : PhotoFileMetadataWriter {
     public WebpMetadataWriter(string filepath) {
-        base (filepath, PhotoFileFormat.TIFF);
+        base (filepath, PhotoFileFormat.WEBP);
     }
 
     public override void write_metadata(PhotoMetadata metadata) throws Error {