NEO4J v5.x compatibility with loader scripts

[rlustemberg]

The current version of the loader has become completely obsolete once version 5 of NEO4J was made available.
In particular, USING PERIODIC COMMIT has been removed from the api. Also the CREATE INDEX methods have been changed.
Also, it's necessary to make the script compatible with the latest version of py2neo and current versions of python.
To summarise:

• The Cypher templates and templating code need to be updated to use the current Cypher api
• DB connection code needs to be made compatible with py2neo versions > 4.x.x .
• Script in general needs to be compatible with latest version of py2neo, which can connect to NEO4J v 5.x
• Script in general needs to run in current versions of Python
• Documentation needs to be updated

I'll provide a PR with the needed changes. Regarding the docs, I'll make a best effort, probably through an addendum

[rlustemberg]

Here's the PR:
https://github.com/IHTSDO/snomed-database-loader/pull/57

[nickdevrekerdelta]

hello

is there a way to just use the older versions? and what is needed? thx