Explicitly set workspaceId column as uuid type to ease pg LEFT JOIN (#15430)

Pg scan was redundant because historically the workspaceId was
`varchar`, even though below migration won't change that we had a look
to workspaceId col declaration across the codebase

packages/twenty-server/src/engine/core-modules/webhook/webhook.entity.ts

@@ -42,7 +42,7 @@ export class WebhookEntity {
   secret: string;
 
   @Field(() => UUIDScalarType)
-  @Column('uuid')
+  @Column({ nullable: false, type: 'uuid' })
   workspaceId: string;
 
   @Field()