Allow read-only replicas work even when the context extension is enabled

[drnextgis]

It fixes the following issue:

postgis=> SELECT search('{}');
NOTICE:  SEARCH: {}
NOTICE:  FILTER: <NULL>
ERROR:  cannot execute SELECT FOR UPDATE in a read-only transaction
CONTEXT:  SQL statement "SELECT *         FROM search_wheres WHERE md5(_where)=inwhere_hash FOR UPDATE"
PL/pgSQL function where_stats(text,boolean,jsonb) line 57 at SQL statement
PL/pgSQL function search(jsonb) line 65 at assignment

I proposed the test in another PR: #297

[drnextgis]

@bitner I wanted to kindly ask if you could take a moment to review the PR 🙏

[drnextgis]

@bitner are there any plans to cut a new release soon?

[mindflayer]

Hi there, I am sorry for stepping in, but we helped with spotting the issue and fixing it, and just knowing when this will be available would really help my team in Satellogic to plan the next steps. Thanks!