Drop support for PG 9.5.

Related: https://github.com/PostgREST/postgrest/pull/2038

api.rst

@@ -193,8 +193,6 @@ The :code:`fts` filter mentioned above has a number of options to support flexib
 
     curl "http://localhost:3000/tsearch?my_tsv=not.wfts(french).amusant"
 
-Using phrase search mode requires PostgreSQL of version at least 9.6 and will raise an error in earlier versions of the database.
-
 Using `websearch_to_tsquery` requires PostgreSQL of version at least 11.0 and will raise an error in earlier versions of the database.
 
 .. _v_filter:
@@ -1677,10 +1675,6 @@ A single row UPSERT can be done by using :code:`PUT` and filtering the primary k
 
 All the columns must be specified in the request body, including the primary key columns.
 
-.. note::
-
-  Upsert features are only available starting from PostgreSQL 9.5 since it uses the `ON CONFLICT clause <https://www.postgresql.org/docs/current/sql-insert.html#SQL-ON-CONFLICT>`_.
-
 .. _delete:
 
 Deletions

auth.rst

@@ -65,7 +65,7 @@ You can use row-level security to flexibly restrict visibility and access for th
 
 We want to enforce a policy that ensures a user can see only those messages sent by him or intended for him. Also we want to prevent a user from forging the message_from column with another person's name.
 
-PostgreSQL (9.5 and later) allows us to set this policy with row-level security:
+PostgreSQL allows us to set this policy with row-level security:
 
 .. code-block:: postgres
 

install.rst

@@ -106,7 +106,7 @@ For a complete reference of the configuration file, see :ref:`configuration`.
 PostgreSQL dependency
 ---------------------
 
-To use PostgREST you will need an underlying database. We require PostgreSQL 9.5 or greater. You can use something like `Amazon RDS <https://aws.amazon.com/rds/>`_ but installing your own locally is cheaper and more convenient for development. You can also run PostgreSQL in a :ref:`docker container<pg-in-docker>`.
+To use PostgREST you will need an underlying database. We require PostgreSQL 9.6 or greater. You can use something like `Amazon RDS <https://aws.amazon.com/rds/>`_ but installing your own locally is cheaper and more convenient for development. You can also run PostgreSQL in a :ref:`docker container<pg-in-docker>`.
 
 Docker
 ======