Fix shutdown server context cancel error

[laraws]

When I used the source code to build the podsync, after run the ./podsync command, I used ctrl+c to stop the server, then the log display the server shutdown failed, the detailed log displayed below:

INFO[2022-02-10T10:50:36+08:00] shutting down web server                     
ERRO[2022-02-10T10:50:36+08:00] server shutdown failed                        error="context canceled"
INFO[2022-02-10T10:50:36+08:00] shutting down cron                           
INFO[2022-02-10T10:50:36+08:00] Got compaction priority: {level:0 score:1.73 dropPrefixes:[]} 
INFO[2022-02-10T10:50:36+08:00] gracefully stopped                           

So I fixed this error. And the log displays like this now:

INFO[2022-02-11T11:32:42+08:00] shutting down web server                     
INFO[2022-02-11T11:32:42+08:00] shutting down cron                           
INFO[2022-02-11T11:32:42+08:00] Got compaction priority: {level:0 score:1.73 dropPrefixes:[]} 
INFO[2022-02-11T11:32:42+08:00] Running for level: 0                         
INFO[2022-02-11T11:32:42+08:00] LOG Compact 0->1, del 1 tables, add 1 tables, took 2.300744ms 
INFO[2022-02-11T11:32:42+08:00] Compaction for level: 0 DONE                 
INFO[2022-02-11T11:32:42+08:00] Force compaction on level 0 done             
INFO[2022-02-11T11:32:42+08:00] gracefully stopped