Adding missing properties to Exec TS defs (#225)

diff --git a/lib/main.d.ts b/lib/main.d.ts
index b6fedb6..212a183 100644
--- a/lib/main.d.ts
+++ b/lib/main.d.ts
@@ -250,6 +250,7 @@
         code: string;
         binary?: boolean;
         main?: string;
+        image?: string;
     }
 
     interface Sequence {