[FR] Add the `increment` method for realtime database

[Tom3652]

Is your feature request related to a problem? Please describe.

Please see this SO question that i have asked.

Describe the solution you'd like

I would like to be able to increment a value server side such as :

from firebase_admin import db

realtime_db = db.reference(path="/", app=app, url="myurl")
realtime_db.update({
   f"chats/{uid}/num": db.increment(1),
})

Describe alternatives you've considered

The alternative described in the SO question as an answer.

[google-oss-bot]

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