Update VisualStudio.gitignore

Ignore backup files from editing reports

VisualStudio.gitignore

@@ -257,6 +257,7 @@ ServiceFabricBackup/
 *.bim.layout
 *.bim_*.settings
 *.rptproj.rsuser
+*- Backup*.rdl
 
 # Microsoft Fakes
 FakesAssemblies/