Update to OLS4 if needed

[sneumann]

Hi,
on 30.10.2023 the OLS system will be upgraded to OLS4. Website promises:

Migrating to the OLS4 API should be as simple as replacing ols with ols4 in the path. For example,
    http://www.ebi.ac.uk/ols/api/ontologies (before)
    http://www.ebi.ac.uk/ols4/api/ontologies (after)

Otherwise the OLS4 tracker with already a few caveats is at https://github.com/EBISPOT/ols4/issues
Yours,
Steffen

[sneumann]

And indeed, things are not fully functional with OLS4:

1. it is still possible to search terms
2. when hitting the insert button, the message ScriptError: SyntaxError: "undefined" is not valid JSON appears just below the search button.

Yours, Steffen

[sneumann]

This is being tackled in #40