fix: hoist function settings with memory units properly

f9ee1f7e introduced the hoisting of function settings as transaction-scoped
settings. However, this currently doesn't work with memory units, which are
case-sensitive according to the docs [1]. This removes the lowercasing of
values to make them work.

This is not added to the CHANGELOG, because this feature was not released, yet.

[1]: https://www.postgresql.org/docs/current/config-setting.html#CONFIG-SETTING-NAMES-VALUES

src/PostgREST/SchemaCache.hs

@@ -456,7 +456,7 @@ funcsSqlQuery pgVer = [q|
     SELECT
       array_agg(row(
         substr(setting, 1, strpos(setting, '=') - 1),
-        lower(substr(setting, strpos(setting, '=') + 1))
+        substr(setting, strpos(setting, '=') + 1)
       )) as kvs
     FROM unnest(proconfig) setting
     WHERE setting not LIKE 'default_transaction_isolation%'