fix(patient): error in age calculation (backport #421)

[mergify[bot]]

The age of a patient was being bad calculated: between April 1st of different years, will be only years of difference, however, it is not working like that.

See that from April 1st of 2019 to now, April 1st of 2024 there are just 5 years of difference.

Now, using moment library, that is already installed, the age is being well calculated.

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This is an automatic backport of pull request #421 done by Mergify.

[mergify[bot]]

Cherry-pick of 9258c1c3200430b6b7d1c6497b48e5a1aaf3b105 has failed:

On branch mergify/bp/version-15-hotfix/pr-421
Your branch is up to date with 'origin/version-15-hotfix'.

You are currently cherry-picking commit 9258c1c.
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Unmerged paths:
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    both modified:   healthcare/healthcare/doctype/patient/patient.js

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