[FIX] openupgrade_merge_records: safely merge jsonb and serialized fields

[xaviedoanhduy]

when merging records using openupgrade_merge_records.merge_records(),
the helper apply_operations_by_field_type attempted to apply the |= operator directly on string values. however jsonb fields may be wrapped types (e.g. psycopg2.extras.Json), causing:
TypeError: unsupported operand type(s) for |=: 'dict' and 'str'

maybe not as expected the result returned like method="sql" (ref), will return dict value like {"en_US": "Awaiting"}. but unfortunately in method="orm" even though name field in database is jsonb but in ORM level it is still Char type and return a string like "Awaiting" so the error occurred.

this proposed fix will convert string value to dict based on current language (mostly en_US). In case field type is Serialized, the old logic remains the same because they are mostly dicts. And in python versions like 3.8 it seems that the |= operator is not supported yet so I replaced it with the .update() function

on this occasion also corrected the warning sush as: UserWarning: unsupported operand type(s) for "==": 'res.company()' == '1' in the second commit 96be2e9

[StefanRijnhart]

@MiquelRForgeFlow Why are you asking me for a review without reviewing yourself?

[MiquelRForgeFlow]

I forgot 😅