notmuch: fix bad copy-paste in MsgModifyTags logging

Print "failed to remove tag" instead of "failed to add tag" when
removing tag failed.

Fixes: 5ca6022d00 ("lint: ensure errors are at least logged (errcheck)")
Signed-off-by: Julian Pidancet <julian.pidancet@oracle.com>
Acked-by: Robin Jarry <robin@jarry.cc>
Acked-by: Tim Culverhouse <tim@timculverhouse.com>

worker/notmuch/lib/database.go

@@ -315,7 +315,7 @@ func (db *DB) MsgModifyTags(key string, add, remove []string) error {
 			for _, t := range remove {
 				err := msg.RemoveTag(t)
 				if err != nil {
-					logging.Warnf("failed to add tag: %v", err)
+					logging.Warnf("failed to remove tag: %v", err)
 				}
 			}
 		})