wip use timestamp type for mysql and Date type for TS

packages/slackbot-proxy/src/entities/relation-mock.ts

@@ -49,7 +49,7 @@ export class RelationMock {
   @Column({ type: 'json' })
   permittedChannelsForEachCommand : PermittedChannelsForEachCommand
 
-  @Column({ type: 'bigint' })
+  @Column({ type: 'timestamp' })
   expiredAtCommands: number;
 
   getDistanceInMillisecondsToExpiredAt(baseDate:Date):number {

packages/slackbot-proxy/src/entities/relation.ts

@@ -36,7 +36,7 @@ export class Relation {
   @Column('simple-array')
   supportedCommandsForSingleUse: string[];
 
-  @Column({ type: 'bigint' })
+  @Column({ type: 'timestamp' })
   expiredAtCommands: number;
 
   getDistanceInMillisecondsToExpiredAt(baseDate:Date):number {