AC-743 NPE removed at PatientDashboard

[rishabh-997]

Description of what I changed

PatientDto was not excepting the null value for the photo which I changed so it can accept.

Issue I worked on

JIRA Issue: https://issues.openmrs.org/browse/AC-743

Checklist: I completed these to help reviewers :)

• My pull request only contains ONE single commit
  (the number above, next to the 'Commits' tab is 1).

• I have added tests to cover my changes. (If you refactored
  existing code that was well tested you do not have to add tests)

• All new and existing tests passed.

• My pull request is based on the latest changes of the master branch.

[codecov-io]

Codecov Report

Merging #719 into master will not change coverage by %.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master     #719   +/-   ##
=======================================
  Coverage   11.90%   11.90%           
=======================================
  Files         236      236           
  Lines       10502    10502           
  Branches     1006     1006           
=======================================
  Hits         1250     1250           
  Misses       9171     9171           
  Partials       81       81           

Impacted Files	Coverage Δ
.../main/java/org/openmrs/mobile/models/PatientDto.kt	40.00% <0.00%> (ø)

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