[simple-scan] Fix setting source for Epson scanner, where Flatbed is named 'Document Table'

[Bartosz <bkosiorek src gnome org>]

commit 451e4a17a836bea0921e13c1dd796f77128f6bfb
Author: Bartosz Kosiorek <gang65 poczta onet pl>
Date:   Sat Mar 28 23:19:44 2020 +0100

    Fix setting source for Epson scanner, where Flatbed is named 'Document Table'

 src/scanner.vala | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/scanner.vala b/src/scanner.vala
index 02bc0de..0bef3e3 100644
--- a/src/scanner.vala
+++ b/src/scanner.vala
@@ -931,7 +931,8 @@ public class Scanner : Object
                     Sane.I18N ("Flatbed"),
                     "FlatBed",
                     "Normal",
-                    Sane.I18N ("Normal")
+                    Sane.I18N ("Normal"),
+                    "Document Table" /* Epson scanners, eg. ET-3760 */ 
                 };
 
                 string[] adf_sources =