Fix Bug - Delivery details not updated

[zhonghan721]

Delivery details associated with edited customer are not updated automatically

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (e3ad703) 83.98% compared to head (37cda12) 83.95%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #482      +/-   ##
============================================
- Coverage     83.98%   83.95%   -0.03%     
- Complexity      995     1002       +7     
============================================
  Files           121      121              
  Lines          2959     2979      +20     
  Branches        353      357       +4     
============================================
+ Hits           2485     2501      +16     
+ Misses          389      388       -1     
- Partials         85       90       +5     

Files	Coverage Δ
...rc/main/java/seedu/address/model/DeliveryBook.java	86.11% <100.00%> (+0.39%)	⬆️
src/main/java/seedu/address/model/Model.java	100.00% <ø> (ø)
...rc/main/java/seedu/address/model/ModelManager.java	99.46% <100.00%> (+<0.01%)	⬆️
...edu/address/model/delivery/UniqueDeliveryList.java	88.88% <100.00%> (+0.20%)	⬆️
...in/java/seedu/address/model/delivery/Delivery.java	84.33% <50.00%> (+0.42%)	⬆️
...s/logic/commands/customer/CustomerEditCommand.java	92.66% <77.27%> (-3.94%)	⬇️

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[jianyangg]

Close #481

[juliusgambe]

Some general comments

[juliusgambe]

Thanks. LGTM